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  • 1.
    Anand, Srinivasan
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    InP-based two dimensional photonic crystals: A material and processing perspective2008In: ICTON 2008: PROCEEDINGS OF 2008 10TH ANNIVERSARY INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS, VOL 2 / [ed] Marciniak, M, NEW YORK: IEEE , 2008, 25-25 p.Conference paper (Refereed)
    Abstract [en]

    The talk will address fabrication and characterization of InP-based two-dimensional (2D) photonic crystals (PhCs). The emphasis will be on material and processing issues. In particular, high aspect ratio etching of PhCs in the InP-based materials will be discussed, including feature-size dependent etching and its impact on the optical properties of PhCs. The physical basis for modification of carrier lifetimes of quantum wells in etched PhCs due to the so-called accumulated side-wall damage and methods to control carrier lifetimes relevant for emitter and switching applications will be discussed. Fundamental investigations of carrier transport across PhC structures will be reported and a new method to determine the etched side-wall Surface potential will be demonstrated.

  • 2.
    Anand, Srinivasan
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Berrier, Audrey
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ferrini, R.
    Houdre, R.
    Kamp, M.
    Forchel, A.
    Towards realization of high quality 2D-photonic crystals in InP/GaInAsP/InP2004In: 2004 International Conference on Indium Phosphide and Related Materials, Conference Proceedings, 2004, 311-313 p.Conference paper (Refereed)
    Abstract [en]

    Two-dimensional photonic crystals (PhCs) were etched into InP/GaInAsP/InP planar waveguides using chlorine based chemical assisted ion beam etching (CAIBE). Etching mechanisms and process parameters crucial for high quality PhC definition are discussed, with special attention to the lag-effect. The processed PhCs were optically characterized by measuring transmission through simple slabs and one-dimensional cavities. The optical properties inside the photonic bandgap are much better compared to both previously reported CAME results and results obtained with other etching methods. In particular, we measured a record quality factor of 310 for one-dimensional cavities fabricated in this material system.

  • 3.
    Anand, Srinivasan
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Qiu, Min
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Swillo, Marcin
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Jaskorzynska, Bozena
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karlsson, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    High aspect ratio etching and characterization of 2D-photonic crystals in InP/InGaAsP/InP heterostructures2004In: Photonics: Design, Technology, And Packaging / [ed] Jagadish, C; Choquette, KD; Eggleton, BJ; Nener, BD; Nugent, KA, SPIE - International Society for Optical Engineering, 2004, 78-89 p.Conference paper (Refereed)
    Abstract [en]

    We report on the fabrication and characterization of 2D photonic crystals (PhCs) in InP/InGaAsP/InP heterostructures. It is demonstrated that Ar/C12 based chemically assisted ion beam etching (CAIBE) is a very promising method to obtain high aspect ratio etching of PhCs in the InP-based materials. With this process, it is possible to obtain PC-holes as deep as 3 microns even for feature (PhC-hole) sizes as small as 200-250 nm. The optical characteristics of the fabricated PhC-based elements/devices such as line-defect waveguides, in-plane resonant cavities and drop-filter based on contra-directional coupling will be reported. The devices were measured using end-fire coupling and the obtained results were simulated using the 2D finite difference time domain (FDTD) method including an effective loss-approximation. The etched PhC-waveguides show low transmission losses, less than 1 dB/100 mum. A quality factor of 400 for a 6 micron long cavity with 6-hole mirrors is obtained. Finally, drop-functionality in a PhC-based filter using contra-directional coupling is demonstrated.

  • 4.
    Anand, Srinivasan
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Semiconductor Materials, HMA (Closed 20120101).
    Shahid, Naeem
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Semiconductor Materials, HMA (Closed 20120101).
    Naureen, Shagufta
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Semiconductor Materials, HMA (Closed 20120101).
    Li, Mingyu
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Semiconductor Materials, HMA (Closed 20120101). Zhejiang University, Hangzhou, China.
    Swillo, Marcin
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Semiconductor Materials, HMA (Closed 20120101).
    InP-based photonic crystal waveguide filters2010In: 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010, 2010, 104-105 p.Conference paper (Refereed)
  • 5.
    Anand, Srinivasan
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Shahid, Naeem
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Swillo, Marcin
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    InP-Based Photonic Crystal Waveguide Technology for Filtering and Sensing Applications2011In: 2011 13TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON), NEW YORK: IEEE , 2011Conference paper (Refereed)
    Abstract [en]

    Photonic crystal (PhC) components in InP-based materials are of practical importance not only for their unique properties but also for integration with conventional optoelectronic components on InP substrate. Several PhC devices in the substrate approach such as filters, lasers, and waveguides have been demonstrated [1,2] and this has been possible due to the development of deep etching of PhCs in InP [3].

  • 6. Aubin, G.
    et al.
    Talneau, A.
    Uddhammar, Anna
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Highly dispersive photonic crystal-based guiding structures2006In: CLEO/QELS 2006, Optical Society of America, 2006, 972-974 p.Conference paper (Refereed)
    Abstract [en]

    Propagating modes supported by Photonic-Crystal guiding structures can demonstrate very high group velocity dispersion close to a cut-off. We investigate here the wavelength dependence of the dispersion for different Photonic Crystal structures.

  • 7.
    Awan, Kashif Masud
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Sanatinia, Reza
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Nanostructuring of GaAs with tailored topologies using colloidal lithography and dry etching2014In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 32, no 2, 021801- p.Article in journal (Refereed)
    Abstract [en]

    The authors report on the fabrication of GaAs nanopillars with different profiles/topologies using colloidal lithography and dry etching. GaAs nanopillars with different shapes and dimensions were successfully fabricated using inductively coupled plasma reactive ion etching. Two different etch chemistries CH4/H-2/Cl-2 and Ar/Cl-2 were investigated. The fabricated nanopillar arrays had a typical period of similar to 500 nm, and the depths could be varied from a few nanometers to 4 mu m. The CH4/H-2/Cl-2 chemistry with optimized gas flows and plasma powers is shown to produce nanopillars with smooth sidewalls compared to those fabricated with the Ar/Cl-2 chemistry. The GaAs nanopillar arrays have appreciably lower reflectivities in the measured wavelength range from 400 to 850 nm and are typically one order of magnitude lower compared to planar GaAs, which shows their potential for photovoltaic applications.

  • 8. Benisty, H.
    et al.
    Weisbuch, C.
    Olivier, S.
    Houdré, R.
    Ferrini, R.
    Leuenberger, D.
    Wild, B.
    Lombardet, B.
    Qiu, Min
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karlsson, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Swillo, Marcin
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Jazkorzynska, B.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Agio, M.
    Kafesaki, M.
    Soukoulis, C. M.
    Talneau, A.
    Kamp, M.
    Forchel, A.
    Moosburger, J.
    Happ, T.
    Duan, G. -H
    Cuisin, C.
    Chandouineau, J. -P
    Drisse, O.
    Gaborit, F.
    Legouézigou, L.
    Legouézigou, O.
    Lelarge, F.
    Poingt, F.
    Pommereau, F.
    Thedrez, B.
    Low-loss photonic-crystal and monolithic InP integration: Bands, bends, lasers, filters2004In: Photonic Crystal Materials and Devices II, SPIE - International Society for Optical Engineering, 2004, 119-128 p.Conference paper (Refereed)
    Abstract [en]

    Practical realizations of 2D (planar) photonics crystal (PhC) are either on a membrane or etched through a conventional heterostructure. While fascinating objects can emerge from the first approach, only the latter approach lends itself to a progressive integration of more compact PhC's towards monolithic PICs based on InP. We describe in this talk the various aspects from technology to functions and devices, as emerged from the European collaboration "PCIC". The main technology tour de force is deep-etching with aspect ratio of about 10 and vertical sidewall, achieved by three techniques (CAIBE, ICP-RIE, ECR-RIE). The basic functions explored are bends, splitters/combiners, mirrors, tapers, and the devices are filters and lasers. At the end of the talk, I will emphasize some positive aspects of "broad" multimode PhC waveguides, in view of compact add-drop filtering action, notably.

  • 9. Benyattou, T.
    et al.
    Martin, M.
    Orobtchouk, R.
    Talneau, A.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Optical Bloch waves studied by near optical field microscopy2005In: Journal of the Korean Physical Society, ISSN 0374-4884, E-ISSN 1976-8524, Vol. 47, S72-S75 p.Article in journal (Refereed)
    Abstract [en]

    Photonic bandgap structures are very promising for the integration of optical function at the nanoscale level and particularly 2D structures perforated on a slab waveguide. In this context, photonic crystal waveguides obtained by removing rows of holes in the periodic structure are very interesting. We will present here, results of near field optical microscopy conducted on PCW. With a Fourier transform analysis of the image, we can image the Bloch waves propagating in the waveguide. The results are compared to FDTD simulations and we will show that the images obtained correspond to the electric field. Such result allows us to study the interaction of the optical tip with the electromagnetic field. 2D FDTD simulations of 1D photonic crystal interaction with a SNOM tip is presented. The results obtained confirm that the SNOM signal is mainly related to the electric field.

  • 10.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Ferrini, R.
    Ecole Polytech Fed Lausanne, Lab Optoelect & Mat Mol.
    Talneau, A.
    CNRS, LPN.
    Houdré, R.
    Ecole Polytech Fed Lausanne, Inst Photon Elect Quant.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Impact of feature-size dependent etching on the optical properties of photonic crystal devices2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 103, no 9, 096106-1-096106-3 p.Article in journal (Refereed)
    Abstract [en]

    Feature size dependence in Ar/Cl-2 chemically assisted ion beam etching of InP-based photonic crystals (PhCs) and its influence on the optical properties of PhC devices operating in the band gap are investigated. The analysis of the measured quality factors, the determined mirror reflectivities, and losses of one-dimensional Fabry-Perot cavities clearly demonstrates the importance of feature-size dependent etching. The optical properties show a dramatic improvement up to a hole depth of about 3.5 mu m that is primarily due to a significant reduction in extrinsic losses. However, beyond this hole depth, the improvement is at a lower rate, which suggests that extrinsic losses, although present, are not dominant.

  • 11.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Malm, Gunnar
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Electrical conduction through a 2D InP-based photonic crystal - art. no. 63220J2006In: Tuning the Optic Response of Photonic Bandgap Structures III / [ed] Braun, PV; Weiss, SM, 2006, Vol. 6322, J3220-J3220 p.Conference paper (Refereed)
    Abstract [en]

    This work investigates the current transport across two-dimensional PhCs dry etched into InP-based low-index-contrast vertical structures using Ar/Cl-2 chemically assisted ion beam etching. The electrical conduction through the PhC field is influenced by the surface potential at the hole sidewalls, which is modified by dry etching. The measured current-voltage (I-V) characteristics are linear before but show a current saturation at higher voltages. This behaviour is confirmed by simulations performed by ISE-TCAD software. We investigate the dependence of the conductance of the PhC area as a function of the geometry of the photonic crystal as well as the material parameters. By comparing the experimental and simulated conductance of the PhC, we deduce that the Fermi level is pinned at 0.1 eV below the conduction band edge. The method presented here can be used for evaluating etching processes and surface passivation methods. It is also applicable for other material systems and sheds new light on current driven PhC tuning.

  • 12.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Talneau, A.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Feature size effects in Ar/Cl-2 chemically assisted ion beam etching of InP-based protonic crystals2006In: 2006 International Conference on Indium Phosphide and Related Materials Conference Proceedings, NEW YORK: IEEE , 2006, 341-344 p.Conference paper (Refereed)
    Abstract [en]

    This work addresses feature size effects (the lag-effect and roughness development) in chemically assisted ion beam etching (CAIBE) etching of InP-based photonic crystals. Photonic crystal fields The slope of the etch,with varying hole size and periods were etched with different etching times. depth versus diameter cures (lag-curves) reveals an aspect ratio dependence, with an etch limiting aspect ratio of the order of 25. A model of the etch rate specific to Ar/Cl-2 CAIBE is proposed. We calculate the etch rate using a physico-chemical model which takes in to account the effect of Ar-ion sputtering and surface chemical reactions. lit addition, it combines the aspect ratio dependence of the gas conductance of the etched holes. Finally, the bottom roughness of the etched holes is examined; its origin and evolution are discussed.

  • 13.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Talneau, A.
    Ferrini, R.
    Houdre, R.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Feature size effects in chemically assisted ion beam etching of InP-based photonic crystals - art. no. 6327072006In: Nanoengineering: Fabrication, Properties, Optics, and Devices III / [ed] Dobisz, EA; Eldada, LA, BELLINGHAM, WA: SPIE-INT SOC OPTICAL ENGINEERING , 2006, Vol. 6327, 32707-32707 p.Conference paper (Refereed)
    Abstract [en]

    This work addresses feature size effects (the lag-effect and roughness development) in chemically assisted ion beam etching (CAIBE) etching of InP-based photonic crystals. Photonic crystal fields with varying hole size and periods were etched with different etching times. The slope of the etch depth versus diameter curves (lag-curves) reveals a hole size dependence, with a critical aspect ratio higher than 25. A model for the etch rate specific to Ar/Cl-2 CAIBE is proposed. We calculate the etch rate using a physico-chemical model which takes in to account the effect of Ar-ion sputtering and surface chemical reactions. In addition, it combines the aspect ratio dependence of the gas conductance of the etched holes. The origin and evolution of the bottom roughness of the etched holes is examined. The impact of the feature size dependence of the etching on the photonic crystal optical properties is then assessed by measuring the quality-factor of one-dimensional Fabry-Perot cavities using the Internal Light Source method, and discussed in terms of hole shape and depth. A systematic trend between the determined quality factor (Q) and the lag-effect is evidenced: Q decreases from about 250 to 60 when the hole depth drops from 5 mu m to 2 mu m.

  • 14.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Mulot, Mikaël
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Talneau, A.
    CNRS, LPN.
    Ferrini, R.
    Ecole Polytech Fed Lausanne, Lab Optoelect Mat Mol.
    Houdre, R.
    Ecole Polytech Fed Lausanne, Inst Photon & Elect Quant.
    Characterization of the feature-size dependence in Ar/Cl2 chemically assisted ion beam etching of InP-based photonic crystal devices2007In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 25, no 1, 1-10 p.Article in journal (Refereed)
    Abstract [en]

    The authors address feature-size dependence in Ar/Cl-2, chemically assisted ion beam etching (CAIBE) in the context of the fabrication of photonic crystal (PhC) structures. They systematically investigate the influence of various parameters such as hole diameter (115-600 nm), etch duration (10-60 min), and ion beam energy (300-600 eV) on PhC etching in InP with Ar/Cl-2, CAIBE. For a 60 min etching at an Ar-ion energy of 400 eV, the authors report an etch depth of 5 mu m for hole diameters d larger than 300 nm; the etch depth is in excess of 3 mu m for d larger than 200 nm. The evolution of roughness at the bottom of the etched holes and its dependence on hole size and etching conditions,is discussed. The physical mechanism of the observed feature-size dependent etching (FSDE) is then discussed and the effect of the process parameters is qualitatively understood using a model combining the effect of ion sputtering and surface chemical reactions. Finally, the effect of FSDE on the PhC optical properties is assessed by measuring the quality factor of one-dimensional Fabry-Perot PhC cavities. The measured quality factors show a clear trend with the etch depth: the cavity Q increases as the etch depth increases.

  • 15.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Mulot, Mikaël
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Malm, Gunnar
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Carrier transport through a dry-etched InP-based two-dimensional photonic crystal2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 12, 123101-1-123101-6 p.Article in journal (Refereed)
    Abstract [en]

    The electrical conduction across a two-dimensional photonic crystal (PhC) fabricated by Ar/Cl-2 chemically assisted ion beam etching in n-doped InP is influenced by the surface potential of the hole sidewalls, modified by dry etching. Carrier transport across photonic crystal fields with different lattice parameters is investigated. For a given lattice period the PhC resistivity increases with the air fill factor and for a given air fill factor it increases as the lattice period is reduced. The measured current-voltage characteristics show clear ohmic behavior at lower voltages followed by current saturation at higher voltages. This behavior is confirmed by finite element ISE TCAD (TM) simulations. The observed current saturation is attributed to electric-field-induced saturation of the electron drift velocity. From the measured and simulated conductance for the different PhC fields we show that it is possible to determine the sidewall depletion region width and hence the surface potential. We find that at the hole sidewalls the etching induces a Fermi level pinning at about 0.12 eV below the conduction band edge, a value much lower than the bare InP surface potential. The results indicate that for n-InP the volume available for conduction in the etched PhCs approaches the geometrically defined volume as the doping is increased.

  • 16.
    Berrier, Audrey
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Mulot, Mikaël
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Swillo, Marcin
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Qiu, Min
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Thylén, Lars
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Talneau, A.
    CNRS, Lab Photon & Nanostruct.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Negative Refraction at Infrared Wavelengths in a Two-Dimensional Photonic Crystal2004In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 93, no 073902Article in journal (Refereed)
    Abstract [en]

    We report on the first experimental evidence of negative refraction at telecommunication wavelengths by a two-dimensional photonic crystal field. Samples were fabricated by chemically assisted ion beam etching in the InP-based low-index constrast system. Experiments of beam imaging and light collection show light focusing by the photonic crystal field. Finite-difference time-domain simulations confirm that the observed focusing is due to negative refraction in the photonic crystal area.

  • 17.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Shi, Yaocheng
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Development of damage and its impact on surface recombination velocities in dry-etched InP-based photonic crystalsManuscript (Other academic)
  • 18.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Shi, Yaocheng
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Siegert, Jörg
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Accumulated sidewall damage in dry etched photonic crystals2009In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 27, no 4, 1969-1975 p.Article in journal (Refereed)
    Abstract [en]

    Evidence for accumulated damage is provided by investigating the effect of etch duration on the carrier lifetime of an InGaAsP quantum well (QW) inside the InP-based photonic crystal (PhC) structures. It is found that once the quantum well is etched through, additional etching reduces the carrier lifetimes from 800 to 70 ps. The surface recombination velocity (SRV) at the exposed hole sidewalls is determined from the measured carrier lifetimes of the PhC fields with different lattice parameters. The observed variation in the SRV with etch duration also confirms the presence of accumulated sidewall damage. It increases from 6x10(3) to 1.2x10(5) cm s(-1) as the etching time increases from 3 to 50 min. A geometric model based on sputtering theory and on the evolution of the hole shape is developed to explain the accumulation of sidewall damage. The model is used to estimate the number of impact events from sputtered species reaching the QW sidewalls, and the variation in the accumulated impact events with etch duration is shown to be qualitatively consistent with the experimental observations. Finally, the results suggest a new method for tailoring the carrier lifetimes in PhC membrane structures.

  • 19.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Shi, Yaocheng
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Siegert, Jörg
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Evidence for accumulated sidewall damage in dry etched photonic crystals2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118Article in journal (Other academic)
  • 20.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Shi, Yaocheng
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Siegert, Jörg
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Srinivasan, Anand
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Impact of dry-etching induced damage in InP-based photonic crystals2008In: PHOTONIC CRYSTAL MATERIALS AND DEVICES VIII, 2008, Vol. 6989, U9890-U9890 p.Conference paper (Refereed)
    Abstract [en]

    In this work variations of the carrier lifetime in a GaInAsP/InP quantum well in two-dimensional PhC structures etched by Ar/Cl-2 chemically assisted ion beam etching as a function of the processing parameters is investigated. It is shown that the deposition conditions of the SiO2 mask material and its coverage as well as other process steps such as annealing affect the carrier lifetimes. However the impact of patterning the semiconductor on the carrier lifetime is dominant, showing over an order of magnitude reduction. For given PhC lattice parameters, the sidewall damage is shown to be directly related to the measured carrier lifetimes. A simple qualitative model based on sputtering theory and assuming a conical hole-shape development during etching is used to explain the experimental results.

  • 21.
    Berrier, Audrey
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Swillo, Marcin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Le Thomas, N.
    Ecole Polytech Fed Lausanne, Inst Photon & Elect Quant.
    Houdré, R.
    Ecole Polytech Fed Lausanne, Inst Photon & Elect Quant.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Bloch mode excitation in two-dimensional photonic crystals imaged by Fourier optics2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no 16, 165116-1-165116-6 p.Article in journal (Refereed)
    Abstract [en]

    Coupling into the Bloch modes of a two-dimensional photonic crystal (PhC) field is investigated by Fourier optics. The PhC was designed to operate in the second band above the air-light line, close to the autocollimation regime for TE polarization. The sample was fabricated in an InP-based heterostructure and an access ridge waveguide provides in-plane excitation of the PhC. The spatial Fourier transform of the field maps obtained from finite-difference time-domain simulations and those calculated by plane-wave expansion are compared to the experimentally obtained equifrequency surfaces (EFS). The shape of the imaged EFS and its variation with the excitation wavelength is shown to be consistent with the theoretical simulations. Finally, the results indicate that if combined with different excitation geometries, Fourier optics can be a powerful technique to assess photonic crystal devices and to design efficient structures.

  • 22. Bowallius, O.
    et al.
    Anand, Srinivasan
    KTH, Superseded Departments, Electronics.
    Evaluation of different oxidation methods for silicon for scanning capacitance microscopy2001In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 4, no 03-jan, 81-84 p.Article in journal (Refereed)
    Abstract [en]

    Different oxides, namely, native, thermal, and wet-chemical (H2SO4 + H2O2 based) oxides on Si are evaluated in the context of scanning capacitance microscopy (SCM). The samples investigated consisted of uniformly doped Si substrates and p-type epitaxial doping-staircase structures with concentrations ranging from 5 x 10(14) to 2 x 10(19) cm(-3) The bias for which the SCM signal (dC/dV) is maximised for the lowest doped region was used for comparing the different oxidation methods. It is shown that for a better evaluation of the surface oxide properties, it is essential to obtain dC/dV curves for a sufficiently large doping range. Best results in terms of low values of flat-band voltages (1 V), uniformity, and consistency across a large doping range were obtained for the wet-chemical oxide. For the native oxide case, the difference in the dC/dV peak bias Values obtained at regions doped to 5 x 10(14) to 10(17) cm(-3) was anomalously large and suggests appreciable distortion of the dC/dV curves. For the same oxidation procedure the full-width at half-maximum of the dC/dV curve obtained on the cleaved surface is typically 2 times larger than that on the planar (100) surface. It is most likely that interface states are responsible for the observed distortion.

  • 23. Bowallius, O.
    et al.
    Anand, Srinivasan
    KTH, Superseded Departments, Electronics.
    Nordell, N.
    Landgren, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karlsson, S.
    Scanning capacitance microscopy investigations of SiC structures2001In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 4, no 03-jan, 209-211 p.Article in journal (Refereed)
    Abstract [en]

    We have applied scanning capacitance microscopy (SCM) to investigate SIC structures grown by vapour-phase epitaxy. The SCM technique is evaluated using n- and p-type doping staircase structures with doping concentrations ranging from 10(16) to 10(20) cm(-3). The n- and p-type doping was obtained by doping SiC with nitrogen and aluminium, respectively. The sample cross-sections for SCM were obtained by simple cleaving. For doping levels above 10(17) cm(-3) the SCM data are consistent with doping data obtained independently from secondary ion mass spectroscopy (SIMS). Treating the samples with diluted hydrofluoric acid significantly improves the SCM signal for the low-doped regions. The SCM technique has been used to investigate doping redistribution in patterned regrowth of n- and p-type SIC around dry-etched mesas. In both cases, contrast variations were seen close to the mesa walls, indicative of doping variations; lower and higher incorporation for p- and n-type, respectively. The observations are shown to be consistent with the expected trends in dopant incorporation in the SiC material.

  • 24. Carlstrom, C. F.
    et al.
    Anand, Srinivasan
    KTH, Superseded Departments, Electronics.
    Characterization of damage in InP dry etched using nitrogen containing chemistries2001In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 19, no 5, 1905-1910 p.Article in journal (Refereed)
    Abstract [en]

    Etching of InP by different ion beam etching processes using chemistries containing nitrogen, such as nitrogen milling, N(CH3)(3) and Ar/N(CH3)(3) based reactive ion beam etching (RIBS), and N-2/CH4/H-2 based chemically assisted ion beam etching (CAIBE), is investigated. The residual surface damage is characterized using I-V characteristics of Au/InP metal-semiconductor (MS) contacts and photoluminescence (PL) yield measurements from near surface quantum wells and bulls InP. The contacts formed on as-etched surfaces, irrespective of the etch process, show ohmic behavior. On the other hand, although the PL yield is reduced for the different processes, the measured intensities show variations which are attributed to passivation of defects by hydrogen. Secondary ion mass spectroscopy (SIMS) was used to check (qualitatively) the presence of nitrogen in the etched and annealed InP samples. SIMS data show the presence of nitrogen in the near surface region of the etched samples, but nitrogen levels drop to background levels upon annealing at typical regrowth conditions (650 degreesC under phosphine flow). Interestingly, the annealing step results not only in a significant recovery of the PL yield, but also in a recovery of Schottky characteristics of the Au contacts formed on the annealed surfaces. These observations show that the etch-induced damage is significantly reduced by annealing and suggests recovery of the near-surface stoichiometry and possibly reduction of nitrogen-related defects.

  • 25. Carmody, C.
    et al.
    Tan, H. H.
    Jagadish, C.
    Douhéret, Olivier
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Maknys, Kestutis
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zou, J.
    Dao, L.
    Gal, M.
    Structural, electrical, and optical analysis of ion implanted semi-insulating InP2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 95, no 2, 477-482 p.Article in journal (Refereed)
    Abstract [en]

    Semi-insulating InP was implanted with MeV P, As, Ga, and In ions, and the resulting evolution of structural properties with increased annealing temperature was analyzed using double crystal x-ray diffractometry and cross sectional transmission electron microscopy. The types of damage identified are correlated with scanning spreading resistance and scanning capacitance measurements, as well as with previously measured Hall effect and time resolved photoluminescence results. We have identified multiple layers of conductivity in the samples which occur due to the nonuniform damage profile of a single implant. Our structural studies have shown that the amount and type of damage caused by implantation does not scale with implant ion atomic mass.

  • 26.
    De Luca, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Sanatinia, Reza
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Swillo, Marcin
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Focused ion beam milling of gallium phosphide nanowaveguides for non-linear optical applications2014In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2014Conference paper (Refereed)
    Abstract [en]

    GaP multilayer slab waveguides were fabricated by FIB milling. Limited transmission properties of the nanostructures, due to appreciable residuals of gallium, were recovered by fspulsed laser exposure. The waveguides were assessed by SHG technique.

  • 27.
    De Luca, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Sanatinia, Reza
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Mensi, Mounir
    KTH, School of Information and Communication Technology (ICT).
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Modal phase matching in nanostructured zincblende semiconductors for second-harmonic generation2017In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2017Conference paper (Refereed)
    Abstract [en]

    Gallium phosphide nanowaveguide arrays, designed to fulfill the phase matching conditions and field-overlap, are characterized by second-harmonic generation. The bandwidth of 30nm with maximum conversion efficiency of 10-3 is measured for 150fs optical pulses.

  • 28.
    De Luca, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Sanatinia, Reza
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Mensi, Mounir
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Anand, Srinivasan
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Modal phase matching in nanostructured zinc-blende semiconductors for second-order nonlinear optical interactions2017In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, no 7, 075303Article in journal (Refereed)
    Abstract [en]

    We demonstrate enhanced second-harmonic generation in arrays of nanowaveguides satisfying modal-phase-matching condition, both theoretically and experimentally. The overlap of interacting fields defined by the fundamental mode of the pump and the second-order mode of the second-harmonic wave is enhanced by the longitudinal component of the nonlinear polarization density. For guided modes with significant longitudinal electric field components, the overlap of fields is comparable to that obtained in the quasi-phase-matching technique leading to higher conversion efficiencies. Thus, the presented method is preferable to achieve higher conversion efficiency in second-order nonlinear processes in nanowaveguides.

  • 29.
    De Luca, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Sanatinia, Reza
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Srinivasan, Anand
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Focused ion beam milling of gallium phosphide nanostructures for photonic applications2016In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 6, no 2, 587-596 p.Article in journal (Refereed)
    Abstract [en]

    We report on the fabrication of gallium phosphide (GaP) nanowaveguides of controlled dimensions, as small as 0.03 μm and aspect ratio in excess of 20, using focused ion beam (FIB) milling. A known limitation of this fabrication process for photonic applications is the formation of gallium droplets on the surface. We demonstrate a post-fabrication step using a pulsed laser to locally oxidize the excess surface gallium on the FIB milled nanostructures. The process significantly reduces the waveguide losses. The surface optical quality of the fabricated GaP nanowaveguides has been evaluated by second-harmonic generation experiments. Surface and bulk contributions to second-order optical nonlinearities have been identified by polarization measurements. The presented method can potentially be applied to other III-V nanostructures to reduce optical losses.

  • 30. de Rossi, S.
    et al.
    Sagnes, I.
    Legratiet, L.
    Talneau, A.
    Berrier, A.
    Mulot, M.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Gentner, J. L.
    Longitudinal mode selection in constricted photonic crystal guides and electrically injected lasers2005In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 23, no 3, 1363-1368 p.Article in journal (Refereed)
    Abstract [en]

    Locally reducing the width of a wide photonic crystal (PhC) waveguide generates a constriction which acts as an internal reflector. We have simulated and measured the spectral behavior of a wide PhC waveguide locally constricted to a narrower PhC waveguide and ended by two cleaved facets, thus generating two coupled cavities. Passive structures as well as electrically injected active structures have been investigated. The multimode behavior of wide PhC waveguides is evidenced to play a deciding role. Modal reflection and transmission at the constriction are simulated and measured on passive PhC waveguides, when varying the constrictions' hole size and length. The spectral behavior of full-PhC electrically pumped lasers including such a constriction is measured and analyzed according to the constriction geometry. Design rules are finally proposed to take advantage of this coupled-cavities behavior for high rejection and high external efficiency monomode laser operation.

  • 31.
    Dev, Apurba
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Dev Choudhury, Bikash
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Abedin, Ahmad
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Fabrication of Periodic Nanostructure Assemblies by Interfacial Energy Driven Colloidal Lithography2014In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 24, no 29, 4577-4583 p.Article in journal (Refereed)
    Abstract [en]

    A novel interfacial energy driven colloidal lithography technique to fabricate periodic patterns from solution-phase is presented and the feasibility and versatility of the technique is demonstrated by fabricating periodically arranged ZnO nanowire ensembles on Si substrates. The pattern fabrication method exploits different interfaces formed by sol-gel derived ZnO seed solution on a hydrophobic Si surface covered by a monolayer of colloidal silica spheres. While the hydrophobic Si surface prevents wetting by the seed solution, the wedge shaped regions surrounding the contact point between the colloidal particles and the Si substrate trap the solution due to interfacial forces. This technique allows fabrication of uniform 2D micropatterns of ZnO seed particles on the Si substrate. A hydrothermal technique is then used to grow well-defined periodic assemblies of ZnO nanowires. Tunability is demonstrated in the dimensions of the patterns by using silica spheres with different diameters. The experimental data show that the periodic ZnO nanowire assembly suppresses the total reflectivity of bare Si by more than a factor of 2 in the wavelength range 400-1300 nm. Finite-difference time-domain simulations of the wavelength-dependent reflectivity show good qualitative agreement with the experiments. The demonstrated method is also applicable for other materials synthesized by solution chemistry.

  • 32.
    Dev Choudhury, Bikash
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Abedin, Ahmad
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Dev, Apurba
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Sanatinia, Reza
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Silicon micro-structure and ZnO nanowire hierarchical assortments for light management2013In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 3, no 8, 1039-1048 p.Article in journal (Refereed)
    Abstract [en]

    We present fabrication and optical characterization of Si microstructure-ZnO nanowire (NWs) hierarchical structures for light management. Random and periodic hierarchical structures constituting Si micro pillar or micro pyramid arrays with overgrown ZnO NWs have been fabricated. Inexpensive colloidal lithography in combination with dry and wet chemical etching is used to fabricate Si microstructures, and ZnO NWs are grown by hydrothermal synthesis. The periodic Si micro pyramid-ZnO NWs hierarchical structure shows broadband antireflection with average reflectance as low as 2.5% in the 300-1000 nm wavelength range. A tenfold enhancement in Raman intensity is observed in this structure compared to planar Si sample. These hierarchical structures with enriched optical properties and high surface to volume ratio are promising for photovoltaic (PV) and sensor applications.

  • 33.
    Dev Choudhury, Bikash
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Anand, Srinivasan
    Rapid thermal annealing treated spin-on doped antireflective radial junction Si nanopillar solar cell2017In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 8, A200-A207 p.Article in journal (Refereed)
    Abstract [en]

    Radial junction nanopillar Si solar cells are interesting for cost effective efficiency improvement. Here, we address a convenient top-down fabrication of Si nanopillar solar cells using spin-on doping and rapid thermal annealing (RTA) for conformal PN junction formation. Broadband suppressed reflection as low as an average of 5% in the 300-1100 nm wavelength range and un-optimized cell efficiency of 7.3% are achieved. The solar cell performance can be improved by optimization of spin-on-doping and suitable surface passivation. Overall, the all RTA processed, spin-on doped nanopillar radial junction solar cell shows a very promising route for low cost and high efficiency thin film solar cell perspectives.

  • 34.
    Dev Choudhury, Bikash
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    RTA treated spin–on doped antireflective radial junction Si nanopillar solar cellManuscript (preprint) (Other academic)
  • 35.
    Dev Choudhury, Bikash
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Casquel, R.
    Banuls, M. J.
    Sanza, F. J.
    Laguna, M. F.
    Holgado, M.
    Puchades, R.
    Maquieira, A.
    Barrios, C. A.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Silicon nanopillar arrays with SiO2 overlayer for biosensing application2014In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 4, no 7, 1345-1354 p.Article in journal (Refereed)
    Abstract [en]

    We present the fabrication of silicon dioxide (SiO2) coated silicon nanopillar array structures and demonstrate their application as sensitive optical biosensors. Colloidal lithography, plasma dry etching and deposition processes are used to fabricate SiO2 coated Si nanopillar arrays with two different diameters and periods. Proof of concept bio recognition experiments are carried out with the bovine serum albumin (BSA)/antiBSA model system using Fourier transform visible and IR spectrometry (FT-VIS-IR) in reflection mode. A limit of detection (LoD) value of 5.2 ng/ml is estimated taking in to account the wavenumber uncertainty in the measurements.

  • 36.
    Dev Choudhury, Bikash
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Sahoo, Pankaj K.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Nanopillar Assemblies with Deterministic Correlated Disorder for Color FilteringManuscript (preprint) (Other academic)
  • 37.
    Dev Choudhury, Bikash
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Sahoo, Pankaj Kumar
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA. Indian Institute of Technology, India.
    Sanatinia, Reza
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Andler, G.
    Stockholm University.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Surface second harmonic generation from silicon pillar arrays with strong geometrical dependence2015In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 40, no 9, 2072-2075 p.Article in journal (Refereed)
    Abstract [en]

    We present experimental demonstration and analysis of enhanced surface second harmonic generation (SHG) from hexagonal arrays of silicon pillars. Three sets of Si pillar samples with truncated cone-shaped pillar arrays having periods of 500, 1000, and 2000 nm, and corresponding average diameters of 200, 585 and 1550 nm, respectively, are fabricated by colloidal lithography and plasma dry etching. We have observed strong dependence of SHG intensity on the pillar geometry. Pillar arrays with a 1000 nm period and a 585 nm average diameter give more than a one order of magnitude higher SHG signal compared to the other two samples. We theoretically verified the dependence of SHG intensity on pillar geometry by finite difference time domain simulations in terms of the surface normal E-field component. The enhanced surface SHG light can be useful for nonlinear silicon photonics, surface/interface characterization, and optical biosensing.

  • 38.
    Dhaka, Veer
    et al.
    Aalto University.
    Oksanen, Jani
    Aalto University.
    Jiang, Hua
    Aalto University.
    Haggren, Tuomas
    Aalto University.
    Nykänen, Antti
    Aalto University.
    Sanatinia, Reza
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Kakko, Joona-Pekko
    Aalto University.
    Huhtio, Teppo
    Aalto University.
    Ruokolainen, Janne
    Aalto University.
    Mattila, Marco
    Aalto University.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Semiconductor Materials, HMA (Closed 20120101).
    Kauppinen, Esko I
    Aalto University.
    Lipsanen, Harri
    Aalto University.
    Aluminum-Induced Photoluminescence Red Shifts in Core-Shell GaAs/AlxGa1-xAs Nanowires2013In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 13, no 8, 3581-3588 p.Article in journal (Refereed)
    Abstract [en]

    We report a new phenomenon related to Al-induced carrier confinement at the interface in core-shell GaAs/AlxGa1-xAs nanowires grown using metal-organic vapor phase epitaxy with Au as catalyst. All AlxGa1-xAs shells strongly passivated the GaAs nanowires, but surprisingly the peak photoluminescence (PL) position and the intensity from the core were found to be a strong function of Al composition in the shell at low temperatures. Large and systematic red shifts of up to similar to 66 nm and broadening in the PL emission from the GaAs core were observed when the Al composition in the shell exceeded 3%. On the contrary, the phenomenon was observed to be considerably weaker at the room temperature. Cross-sectional transmission electron microscopy reveals Al segregation in the shell along six Al-rich radial bands displaying a 3-fold symmetry. Time-resolved PL measurements suggest the presence of indirect electron-hole transitions at the interface at higher Al composition. We discuss all possibilities including a simple shell-core-shell model using simulations where the density of interface traps increases with the Al content, thus creating a strong local electron confinement. The carrier confinement at the interface is most likely related to Al inhomogeneity and/or Al-induced traps. Our results suggest that a low Al composition in the shell is desirable in order to achieve ideal passivation in GaAs nanowires.

  • 39. Dhaka, Veer
    et al.
    Perros, Alexander
    Naureen, Shagufta
    Shahid, Naeem
    Jiang, Hua
    Kakko, Joona-Pekko
    Haggren, Tuomas
    Kauppinen, Esko
    Srinivasan, Anand
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Lipsanen, Harri
    Protective capping and surface passivation of III-V nanowires by atomic layer deposition2016In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 6, no 1, 015016Article in journal (Refereed)
    Abstract [en]

    Low temperature (similar to 200 degrees C) grown atomic layer deposition (ALD) films of AlN, TiN, Al2O3, GaN, and TiO2 were tested for protective capping and surface passivation of bottom-up grown III-V (GaAs and InP) nanowires (NWs), and top-down fabricated InP nanopillars. For as-grown GaAs NWs, only the AlN material passivated the GaAs surface as measured by photoluminescence (PL) at low temperatures (15K), and the best passivation was achieved with a few monolayer thick (2 angstrom) film. For InP NWs, the best passivation (similar to 2x enhancement in room-temperature PL) was achieved with a capping of 2nm thick Al2O3. All other ALD capping layers resulted in a de-passivation effect and possible damage to the InP surface. Top-down fabricated InP nanopillars show similar passivation effects as InP NWs. In particular, capping with a 2 nm thick Al2O3 layer increased the carrier decay time from 251 ps (as-etched nanopillars) to about 525 ps. Tests after six months ageing reveal that the capped nanostructures retain their optical properties. Overall, capping of GaAs and InP NWs with high-k dielectrics AlN and Al2O3 provides moderate surface passivation as well as long term protection from oxidation and environmental attack.

  • 40. Douheret, O.
    et al.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Barrios, C. A.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Characterization of GaAs/AlGaAs laser mesas regrown with semi-insulating GaInP by scanning capacitance microscopy2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 6, 960-962 p.Article in journal (Refereed)
    Abstract [en]

    In this work, cross-sectional scanning capacitance microscopy (SCM) is used to investigate GaAs/AlGaAs buried heterostructure lasers. Laser mesas are buried with GaInP:Fe selectively regrown by hydride vapor phase epitaxy. It is shown that a complete 2D map of the electrical properties of device structure including, delineation of regrown interfaces and electrical nature of the regrown GaInP layer can be obtained. The behavior of the SCM signal with ac bias is used to verify the semi-insulating nature of the regrown layer at different locations of the sample. The measured SCM signal for the regrown GaInP:Fe layer is uniformly zero, indicating very low free carrier densities and confirming semi-insulating properties. This observation strongly suggests, in addition, uniform Fe incorporation in the regrown layers, close to and far away from the mesa. Finally, a nanoscale feature in the SCM contrast appearing as a bright (dark) spot in dC/dV mode (feedback bias mode) is observed at the mesa sidewall close to the interface between the regrown GaInP:Fe and the p-cladding layer. The origin of this contrast is discussed in terms of local band-bending effects and supported by 2D Poisson simulations of the device structure.

  • 41. Douheret, O.
    et al.
    Bonsels, S.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Determination of spatial resolution in atomic-force-microscopy-based electrical characterization techniques using quantum well structures2005In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 23, no 1, 61-65 p.Article in journal (Refereed)
    Abstract [en]

    In this work, a procedure to determine the spatial resolution in scan ning capacitance (SCM) and scanning spreading resistance microscopy (SSRM) is proposed and demonstrated. It is based on profiling of confined carriers (in cross section) in quantum well (QW) structures consisting of QWs with different well widths and interwell spacing. Spatial resolution of sub-5 nm was observed for SSRM with commercially available diamond-coated silicon probes and sub-30 nm for SCM with IrPt5-coated probes. The influence of experimental parameters such as tip-sample bias and tip averaging on lateral resolution is discussed and appropriate measurement conditions for performing high-resolution measurements are highlighted. Finally, it is proposed that such structures can be used not only to select probes appropriate for high resolution measurements, but also in the development of new probes.

  • 42.
    Douheret, Oliver
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Glatzel, T.
    Maknys, K.
    Sadewasser, S.
    Characterization of quantum wells by cross-sectional Kelvin probe force microscopy2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 22, 5245-5247 p.Article in journal (Refereed)
    Abstract [en]

    Cross-sectional Kelvin probe force microscopy (KPFM) in ultrahigh vacuum is used to characterize the electronic structure of InGaAs/InP quantum wells. The KPFM signal shows clear peaks at the position of the quantum wells and exhibits a systematic trend for different wells. It is demonstrated that KPFM is capable of detecting quantum wells as narrow as 5 nm. Evidence for carrier accumulation in the quantum wells is observed. A complete quantitative analysis of the quantum well properties is shown to be impeded by tip averaging effects and due to surface/interface states.

  • 43.
    Douheret, Olivier
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Maknys, Kestutis
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Scanning capacitance microscopy investigations of lnGaAs/InP quantum wells2004In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 459, no 02-jan, 67-70 p.Article in journal (Refereed)
    Abstract [en]

    In this work, cross-sectional scanning capacitance microscopy (SCM) is used to investigate InGaAs/InP (latticed matched) quantum wells grown by metal-organic vapor phase epitaxy. Using n-doped InP as barriers with different doping levels, different InGaAs wells structures (5, 10 and 20 nm) were investigated. The capability of SCM to detect electrons in the quantum wells is demonstrated, showing in addition, a systematic and consistent trend for the different well widths and barrier doping levels. The SCM results are qualitatively consistent with electron distribution obtained for 1D Poisson/Schrodinger simulation. Finally, resolution issues in SCM are discussed in terms of tip averaging effects.

  • 44. El-Kallassi, P.
    et al.
    Ferrini, R.
    Zuppiroli, L.
    Le Thomas, N.
    Houdré, R.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Talneau, A.
    Optical and local tuning of planar photonic crystals infiltrated with organic molecules2007In: Conference on Lasers and Electro-Optics, 2007, CLEO 2007, 2007, 1375-1376 p.Conference paper (Refereed)
    Abstract [en]

    We report on the optical tuning of InP-based planar photonic crystals (PhCs) infiltrated with a photoresponsive liquid crystal system. Preliminary results on the local tuning of PhC devices are also presented.

  • 45. El-Kallassi, P.
    et al.
    Ferrini, R.
    Zuppiroli, L.
    Le Thomas, N.
    Houdré, R.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Talneau, A.
    Optical and local tuning of planar photonic crystals infiltrated with organic molecules2007In: Lasers and Electro-Optics, 2007 European Conference on and the International Quantum Electronics Conference, 2007, 4387041- p.Conference paper (Refereed)
    Abstract [en]

    We report on the optical tuning of InP-based planar photonic crystals infiltrated with a photoresponsive liquid crystal system. Preliminary results on the local tuning of infiltrated structures are also presented.

  • 46. El-Kallassi, Pascale
    et al.
    Ferrini, Rolando
    Zuppiroli, Libero
    Le Thomas, Nicolas
    Houdré, Romuald
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Talneau, Anne
    Optical tuning of planar photonic crystals infiltrated with organic molecules2007In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 24, no 9, 2165-2171 p.Article in journal (Refereed)
    Abstract [en]

    The optical tuning of InP-based planar photonic crystals (PhCs) infiltrated with a photoresponsive liquid crystal system is presented. Photoinduced phase transitions of a liquid crystal blend doped with azobenzene molecules are used to tune the optical response of PhC cavities. This process is found to be reversible and stable. Several tuning conditions are analyzed in terms of the blend phase diagram.

  • 47.
    Ferrini, R.
    et al.
    Ecole Polytech Fed Lausanne, Int Photon & Elect Quant.
    Berrier, Audrey
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Dunbar, L. A.
    Ecole Polytech Fed Lausanne, Int Photon & Elect Quant.
    Houdré, R.
    Ecole Polytech Fed Lausanne, Int Photon & Elect Quant.
    Mulot, Mikaël
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    de Rossi, S.
    CNRS, Lab Photon & Nanostruct.
    Talneau, A.
    CNRS, Lab Photon & Nanostruct.
    Minimization of out-of-plane losses in planar photonic crystals by optimizing the vertical waveguide2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 18, 3998-4000 p.Article in journal (Refereed)
    Abstract [en]

    A two-dimensional phenomenological approach previously developed for the modeling of out-of-plane losses in low refractive index contrast planar photonic crystals (PPhCs) is used to study the dependence of the different loss terms on the planar waveguide parameters. It is demonstrated that: (i) Losses can be minimized by designing vertical heterostructures optimized for a given technological process and/or for a given hole shape; and (ii) any small reduction of the loss value has a strong impact on the optical performances of PPhC structures.

  • 48. Ferrini, R.
    et al.
    Leuenberger, D.
    Mulot, M.
    Qiu, Min
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Moosburger, J.
    Kamp, M.
    Forchel, A.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Houdre, R.
    Optical study of two-dimensional InP-based photonic crystals by internal light source technique2002In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 38, no 7, 786-799 p.Article in journal (Refereed)
    Abstract [en]

    We present the first optical study of 2-D photonic crystals (PCs) deeply etched in an InP/GaInAsP step-index waveguide. Following the same internal light source approach proposed by Labilloy and coworkers for the investigation of GaAs-based 2-D PCs, transmission measurements through simple PC slabs and 1-D Fabry-Perot (FP) cavities between PC mirrors were performed. Details are given on the experimental setup which has been implemented with respect to the original scheme and adapted to InP-based systems working at 1.5-mum. 2-D plane-wave expansion and finite difference time-domain (FDTD) methods are used to fit the experimental data. Out-of-plane losses were evaluated according to a recently introduced phenomenological model. In spite of the complex hole morphology in the measured samples, preliminary results are presented which indicate the possibility of separating different loss contributions from finite etch depth and hole shape. As for 1-D cavities, both FDTD and classical theory for planar resonators are applied in order to deduce the optical properties of the PC mirrors. The origin of an anomalously high transmission observed inside the stopgap is discussed and arguments are given to demonstrate the need for further modeling efforts when working in the bandgap regime.

  • 49. Ferrini, R.
    et al.
    Martz, J.
    Zuppiroli, L.
    Wild, B.
    Zabelin, V.
    Dunbar, L. A.
    Houdre, R.
    Mulot, M.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Planar photonic crystals infiltrated with liquid crystals: optical characterization of molecule orientation2006In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, no 9, 1238-1240 p.Article in journal (Refereed)
    Abstract [en]

    Nematic liquid crystals are infiltrated into InP-based planar photonic crystals. Optical measurements as a function of temperature and polarization are used to study the average director field configuration in the nanometer-size holes: a planar equilibrium state is found.

  • 50.
    Hakkarainen, Teppo
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Douheret, Oliver
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Fu, L.
    Tan, H. H.
    Jagadish, C.
    Spatially resolved characterization of InGaAs/GaAs quantum dot structures by scanning spreading resistance microscopy2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 4, 041106- p.Article in journal (Refereed)
    Abstract [en]

    Cross-sectional scanning spreading resistance microscopy (SSRM) is used to investigate stacked InGaAs/GaAs quantum dot (QD) structures with different doping schemes. Spatially resolved imaging of the QDs by SSRM is demonstrated. The SSRM contrast obtained for the QD layers is found to depend on doping in the structure. In the undoped structures both QD-layers and QDs within the layers could be resolved, while in the doped structures the QD layers appear more or less uniformly broadened. The origin of the SSRM contrast in the QD layer in the different samples is discussed and correlated with doping schemes. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3467138]

123 1 - 50 of 122
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