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  • 1.
    Aggerstam, Thomas
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Pinos, Andrea
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Linnarsson, Margareta
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Electron and hole capture cross-sections of Fe acceptors in GaN:Fe epitaxially grown on sapphire2007In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 36, no 12, p. 1621-1624Article in journal (Refereed)
    Abstract [en]

    Carrier trapping of Fe (3+)/Fe2+ deep acceptors in epitaxially grown GaN:Fe on sapphire was studied by time-resolved photoluminescence. For the investigated Fe doping levels on the order of 10(18) cm(-3), the luminescence decay times are strongly dependent on the Fe concentration, indicating that Fe centers act as predominant nonradiative recombination channels. Linear dependence of the decay time on the iron concentration allows estimation of the electron capture cross-section for the Fe3+ ions, which is equal to 1.9 x 10(-15) cm(2). The upper bound for the cross-section of the hole capture of Fe2+ was evaluated as 10 x 10(-15) cm

  • 2. Akram, M. N.
    et al.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Berggren, J.
    Experimental evaluation of carrier transport, gain, T0 and chirp of 1.55 mm MQW structures with different barrier compositions2005In: 31st European Conference on Optical Communications (ECOC 2005), 2005, Institution of Engineering and Technology, 2005, Vol. 2005, no CP502, p. 297-298Conference paper (Refereed)
    Abstract [en]

    Direct carrier transport measurements were performed for different InGaAsP/InGaAlAs MQW test structures. Shallow InGaAlAs barrier QW showed faster carrier transport. Semi-insulating regrown FP lasers with InGaAlAs barrier QW showed improved high temperature operation, modal gain, differential modal gain and chirp.

  • 3. Akram, N. M.
    et al.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Experimental evaluation of carrier transport, gain, T0 and chirp of 1.55 mu;m MQW structures with different barrier compositions2005In: Optical Communication, 2005. ECOC 2005. 31st European Conference on, 2005, Vol. 2, p. 297-298Conference paper (Refereed)
    Abstract [en]

    Direct carrier transport measurements were performed for different InGaAsP/InGaAlAs MQW test structures. Shallow InGaAlAs barrier QW showed faster carrier transport. Semi-insulating regrown FP lasers with InGaAlAs barrier QW showed improved high temperature operation, modal gain, differential modal gain and chirp.

  • 4.
    Akram, Nadeem
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Marcinkevičius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Olsson, Fredrik
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-mu m multiple quantum-well structures2006In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 42, no 7, p. 713-714Article in journal (Refereed)
    Abstract [en]

    In this paper, the effect of barrier bandgap and composition on the optical performance of 1.55-mu m InGaAsP/In-GaAsP and InGaAsP/InGaAlAs multiple quantum-well structures and Fabry-Perot lasers is evaluated experimentally. Direct vertical carrier transport measurements were performed through strain-compensated multiple quantum-well (MQW) test structures using femto-second laser pulse excitation and time-resolved photoluminescence up-conversion method. MQW test structures were grown with different barrier composition (InGaAsP and InGaAlAs) and barrier bandgap (varied from lambda(g) = 1440 to 1260 nm) having different conduction band Delta E-c and valence band discontinuity Delta E-v, while keeping the same InGaAsP well composition for all the structures. The ambipolar carrier transport was found to be faster in the structures with lower valence band discontinuity Delta E-v. Regrown semi-insulating buried heterostructure Fabry-Perot (SIBH-FP) lasers were fabricated from similar QWs and their static light-current-voltage characteristics (including optical gain and chirp spectra below threshold) and thermal characteristics were measured. Lasers with InGaAlAs barrier showed improved high-temperature operation, higher optical gain, higher differential gain, and lower chirp, making them suitable candidates for high-bandwidth directly modulated uncooled laser applications.

  • 5.
    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)
  • 6.
    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, p. 1969-1975Article 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.

  • 7.
    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)
  • 8.
    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, p. U9890-U9890Conference 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.

  • 9. Bertulis, K.
    et al.
    Krotkus, A.
    Aleksejenko, G.
    Pacebutas, V.
    Adomavicius, R.
    Molis, G.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    GaBiAs: A material for optoelectronic terahertz devices2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 20Article in journal (Refereed)
    Abstract [en]

    GaBiAs layers have been grown by molecular beam epitaxy at low (270-330 degrees C) temperatures and were characterized by several experimental techniques. It was shown that the spectral photosensitivity cutoff wavelength reaches similar to 1.4 mu m when the growth temperature is as low as 280 degrees C. Optical pump-terahertz probe measurements made on these layers have evidenced that the electron trapping time decreases with decreasing growth temperature from 20 to about 1 ps. GaBiAs layers were used for manufacturing photoconductive terahertz emitters and detectors, which, when excited with Ti:sapphire laser pulses, have demonstrated a signal bandwidth of 3 THz.

  • 10. Butte, Raphael
    et al.
    Lahourcade, Lise
    UŽdavinys, Tomas Kristijonas
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Callsen, Gordon
    Mensi, Mounir
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Glauser, Marlene
    Rossbach, Georg
    Martin, Denis
    Carlin, Jean-Francois
    Marcinkevičius, Saulius
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Grandjean, Nicolas
    Optical absorption edge broadening in thick InGaN layers: Random alloy atomic disorder and growth mode induced fluctuations2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 3, article id 032106Article in journal (Refereed)
    Abstract [en]

    To assess the impact of random alloying on the optical properties of the InGaN alloy, high-quality InxGa1-xN (0 < x < 0.18) epilayers grown on c-plane free-standing GaN substrates are characterized both structurally and optically. The thickness (25-100 nm) was adjusted to keep these layers pseudomorphically strained over the whole range of explored indium content as checked by x-ray diffraction measurements. The evolution of the low temperature optical absorption (OA) edge line-width as a function of absorption energy, and hence the indium content, is analyzed in the framework of the random alloy model. The latter shows that the OA edge linewidth should not markedly increase above an indium content of 4%, varying from 17 meV to 30 meV for 20% indium. The experimental data initially follow the same trend with, however, a deviation from this model for indium contents exceeding only similar to 2%. Complementary room temperature near-field photoluminescence measurements carried out using a scanning near-field optical microscope combined with simultaneous surface morphology mappings reveal spatial disorder due to growth meandering. We conclude that for thick high-quality pseudomorphic InGaN layers, a deviation from pure random alloying occurs due to the interplay between indium incorporation and longer range fluctuations induced by the InGaN step-meandering growth mode.

  • 11.
    Campi, Roberta
    et al.
    KTH, Superseded Departments, Electronics.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Physics.
    Landgren, Gunnar
    KTH, Superseded Departments, Electronics.
    Studies on the carrier transport in InGaAlAdP/InGaAsP quantum well structures emitting at 1.3 μm2000In: Conference on Lasers and Electro-Optics Europe - Technical Digest, 2000, p. 141-Conference paper (Refereed)
    Abstract [en]

    A novel approach to improve high temperature performance in the IngaAsP lasers was examined by adding aluminum to the barrier,which allows to increase conduction band offset. To find optimal heterostructure parameters, different barrier material compositions were examined in structures with InGaAsP compressively strained wells and tensile strained InGaAlAsP barriers. The MQW structures were fabricated by low pressure MOVPE.

  • 12. Carmody, C.
    et al.
    Tan, H. H.
    Jagadish, C.
    Gaarder, A.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ion-implanted In0.53Ga0.47As for ultrafast optoelectronic applications2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 22, p. 3913-3915Article in journal (Refereed)
    Abstract [en]

    Undoped In0.53Ga0.47As epilayers were implanted with 2- MeV Fe+ ions at doses of 1x10(15) and 1x10(16) cm(-2) at room temperature and annealed at temperatures between 500 and 800 degreesC. Hall-effect measurements show that after annealing, layers with resistivities on the order of 10(5) Omega/square can be achieved. Carrier lifetimes as short as 300 fs are observed for samples annealed at 500 and 600 degreesC. For higher annealing temperatures, characteristic times of the optical response are on the order of a few picoseconds.

  • 13. Carmody, C.
    et al.
    Tan, H. H.
    Jagadish, C.
    Gaarder, A.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ultrafast carrier trapping and recombination in highly resistive ion implanted InP2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 94, no 2, p. 1074-1078Article in journal (Refereed)
    Abstract [en]

    MeV P+ implanted and annealed p-InP, and Fe+ implanted and annealed semi-insulating InP have both been shown to produce the high resistivity, good mobility, and ultrafast optical response desired for ultrafast photodetectors. Hall effect measurements and time resolved photoluminescence were used to analyze the electrical and optical features of such implanted materials. Low temperature annealing was found to yield the fastest response times-130 fs for Fe+ implanted and 400 fs for P+ implanted InP, as well as resistivities of the order similar to10(6) Omega/square. It was found that the electrical activation of Fe-related centers, useful for achieving high resistivities in Fe+ implanted semi-insulating InP, was not fully realized at the annealing temperatures chosen to produce the fastest optical response. Implanting p-InP in the dose regime where type conversion occurs, and subsequent annealing at 500degreesC, produces high resistivities and ultrafast carrier trapping times that are only marginally dose dependent.

  • 14. Chen, M. X.
    et al.
    Perzon, E.
    Andersson, M. R.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Physics.
    Jonsson, S. K. M.
    Fahlman, M.
    Berggren, M.
    1 micron wavelength photo- and electroluminescence from a conjugated polymer2004In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 84, no 18, p. 3570-3572Article in journal (Refereed)
    Abstract [en]

    We report photo- and electroluminescence from an alternating conjugated polymer consisting of fluorene units and low-band gap donor-acceptor-donor (D-A-D) units. The D-A-D segment includes two electron-donating thiophene rings combined with a thiadiazolo-quinoxaline unit, which is electron withdrawing to its nature. The resulting polymer is conjugated and has a band gap of 1.27 eV. The corresponding electro- and photoluminescence spectra both peak at approximately 1 mum. Light-emitting diodes, based on a single layer of the polymer, demonstrated external quantum efficiencies from 0.03% to 0.05%.

  • 15. Gaarder, A.
    et al.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Barrios, C. A.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Time-resolved micro-photoluminescence studies of deep level distribution in selectively regrown GaInP: Fe and GaAs : Fe2002In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 17, no 2, p. 129-134Article in journal (Refereed)
    Abstract [en]

    We apply time-resolved photoluminescence with 1-2 mum spatial resolution for the characterization of deep centre distributions in semi-insulating GaInP:Fe and GaAs:Fe epitaxial layers regrown by hydride vapour phase epitaxy around etched GaAs mesas and GaAs/AlGaAs quantum well laser structures. In InGaP, Fe ions act as the main carrier recombination centres, while in Fe-doped GaAs both the Fe ions and As antisite defects have to be considered. The distribution of Fe ions in InGaP was found to be rather uniform and close to the target value. For GaAs:Fe, the number of ionized Fe and EL2 centres showed a certain increase at the mesa interfaces. In both cases, the high trap concentration was maintained throughout the regrown layers indicating good semi-insulating material properties.

  • 16. Gaarder, A.
    et al.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Barrios, C. A.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Time-resolved micro-photoluminescence studies of dopant distribution in selectively regrown GalnP: Fe around VCSELs2002In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T101, p. 89-91Article in journal (Refereed)
    Abstract [en]

    We apply time-resolved photoluminescence with 1.5 mum spatial resolution for characterization ofcarrier trap distribution in semi-insulating Ga0.51In0.49P:Fe layers regrown around GaAs/AlGaAs circular vertical cavity surface emitting laser mesas using hydride vapour phase epitaxy. The carrier trapping times are in the range from 10 to 15 ps and quite uniformly distributed throughout the burying GaInP:Fe layer, suggesting that the layer is semi-insulating everywhere. Simulations show that, in addition to the Fe dopants, the layer contains other, unintended carrier traps. The photoluminescence spectra reveal that the regrown GaInP:Fe material has several distinct regions with different band gaps. This is attributed to differences in the In/Ga composition and/or CuPt ordering of the GaInP.

  • 17. Gaarder, A.
    et al.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Messmer, E. R.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Dopant distribution in selectively regrown InP: Fe studied by time-resolved photoluminescence2001In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 226, no 4, p. 451-457Article in journal (Refereed)
    Abstract [en]

    We apply time-resolved photoluminescence with 1 mum spatial resolution for the characterization of iron distribution in semi-insulating InP:Fe epitaxial layers regrown by hydride vapor-phase epitaxy around etched mesas. The InP:Fe regrowth was carried out on InP:S mesas etched both along the [110] and [110] crystallographic directions, as well as on InP/InGaAsP in-plane lasers. In all cases, the Fe concentration was found to be close to the target values and showed little variation along the regrown layers.

  • 18. Gautier, S.
    et al.
    Aggerstam, Thomas
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Pinos, Andrea
    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.
    Liu, K.
    Shur, M.
    O'Malley, S. M.
    Sirenko, A. A.
    Djebbour, Z.
    Migan-Dubois, A.
    Moudakir, T.
    OLIgazzaden, A.
    AlGaN/AlN multiple quantum wells grown by MOVPE on AlN templates using nitrogen as a carrier gas2008In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 310, no 23, p. 4927-4931Article in journal (Refereed)
    Abstract [en]

    AlxGa1-xN/AlN multiple quantum wells (MQWs) structures were grown by metalorganic vapour phase epitaxy (MOVPE) on pseudo AlN substrates using nitrogen as a carrier gas. Results of X-ray diffraction (XRD) and reciprocal space mapping (RSM) indicated no sign of strain relaxation in the quantum wells with respect to the AlN substrate. The MQW parameters such as thicknesses, growth rates and material compositions were extracted from XRD measurements and demonstrated an agreement with our growth conditions. No indication of parasitic reactions between ammonia and trimethyl-aluminium (TMAI) was detected in our growth process. Optical measurements revealed well-defined photoluminescence peaks at 288 and 280 nm, which are in a good agreement with the transmission experimental data. The piezoelectric field value in the Studied structures was estimated to be 900kV/cm.

  • 19.
    Gelzinyte, Kristina
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO. Vilnius State Univ, Inst Appl Res, Lithuania.
    Ivanov, Ruslan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zhao, Y.
    Becerra, D. L.
    Nakamura, S.
    DenBaars, S. P.
    Speck, J. S.
    High spatial uniformity of photoluminescence spectra in semipolar (20(2)over-bar1) plane InGaN/GaN quantum wells2015In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 117, no 2, p. 023111-Article in journal (Refereed)
    Abstract [en]

    Scanning near-field optical spectroscopy was applied to study spatial variations of emission spectra at room temperature in semipolar (20 (2) over bar1) InxGa(1-x)N/GaN single quantum wells (QWs) for 0:11 <= x <= 0:36. Photoluminescence (PL) was found to be highly uniform, with peak wavelength deviations and peak intensity deviations divided by average values in the range of 6-12 meV and 0.03-0.07, respectively. Near-field maps of PL parameters showed large, similar to 5 to 10 mu m size areas of similar values, as opposed to 100 nm scale variations, often reported for InGaN QWs. The near-field PL spectra were found to broaden with increasing InN molar fraction. In the low In content QWs, the broadening is primarily determined by the random cation distribution, while for larger InN molar fractions 10 nm scale localization sites with increasingly deeper band potentials are suggested as the linewidth broadening cause.

  • 20. Guina, Mircea
    et al.
    Suomalainen, Soile
    Hakulinen, Tommi
    Okhotnikov, Oleg
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Semiconductor saturable absorbers with recovery time controlled by lattice mismatch2007In: Optical Components and Materials IV / [ed] Shibin Jiang, Michel J. F. Digonnet, 2007, p. 64690P-1-64690P-7Conference paper (Refereed)
    Abstract [en]

    We propose and demonstrate a new method to reduce the absorption recovery time of semiconductor saturable absorber mirrors operating at the 1060-nm wavelength range. The method is based on controlling the amount of nonradiative recombination centers within the absorbing region by incorporating an InGaP epitaxial layer with a relative large lattice mismatch to GaAs (~2.2 %). The defect density within the absorbing region can be controlled by the thickness of a GaAs buffer layer grown between the InGaP lattice mismatched layer and the InGaAs/GaAs quantum-wells. For thickness of the GaAs buffer of ∼110 nm and∼570 nm the absorption recovery time was∼5 ps and ∼10 ps, respectively. It is important to note that the fast recovery time was achieved without degrading the nonlinear optical properties of the saturable absorber mirror. The practicality of the structures was proved by demonstrating a reliable self-starting operation of a mode-locked Yb-doped fiber laser.

  • 21. Guina, Mircea
    et al.
    Tuomisto, Pietari
    Okhotnikov, Oleg
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Mizohata, Kenichiro
    Keinonen, Juhani
    Semiconductor saturable absorbers with recovery time controlled through growth conditions2007In: Solid State Lasers XVI: Technology and Devices / [ed] Hanna J. Hoffman, Ramesh K. Shori, Norman Hodgson, 2007, p. 645113-1-645113-7Conference paper (Refereed)
    Abstract [en]

    We discuss a new method to shape the temporal response of saturable absorption in semiconductors. In particular, we investigate the possibility to control independently the absorption recovery time of each quantum-well forming the semiconductor absorber. The recovery time is tailored by irradiation with nitrogen ions produced by an RF-plasma source. The irradiation is performed in-situ as one step of the epitaxial growth process; the quantum-wells are individually exposed to a flux of N-ions after they are grown. The amount of non-radiative recombination centers within the quantum-wells is strongly related to the time interval during which the N-ions flux is active and to the thickness of the semiconductor layer grown on top of each quantum-well before the irradiation is performed. We apply this method to fabricate fast semiconductor saturable absorbers operating in the 1-μm wavelength range. The absorption recovery time could be changed from 300 ps to 10 ps without degradation of the nonlinear optical response. The practicality of the design is finally proved by using the semiconductor saturable absorbers for mode-locking Yb-doped fiber lasers.

  • 22.
    Ivanov, R.
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Marcinkevičius, Saulius
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    UŽdavinys, Tomas Kristijonas
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Kuritzky, L. Y.
    Nakamura, S.
    Speck, J. S.
    Scanning near-field microscopy of carrier lifetimes in m-plane InGaN quantum wells2017In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 110, no 3, article id 031109Article in journal (Refereed)
    Abstract [en]

    Time-resolved scanning near-field photoluminescence (PL) spectroscopy was applied to map carrier lifetimes in wide m-plane InGaN/GaN quantum wells grown on on-axis and miscut substrates. Both radiative and nonradiative lifetimes were found to be spatially nonuniform. Lifetime variations were smaller for quantum wells grown on miscut, as compared to on-axis substrates. Correlation with surface topography showed that largest deviations of recombination times occur at +c planes of pyramidal hillocks of the on-axis sample. Observed correlation between radiative lifetimes and PL peak wavelength was assigned to a partial electron localization.

  • 23.
    Ivanov, Ruslan
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Zhao, Y.
    Becerra, D. L.
    Nakamura, S.
    DenBaars, S. P.
    Speck, J. S.
    Impact of carrier localization on radiative recombination times in semipolar (2021) plane InGaN/GaN quantum wells2015In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 107, no 21, article id 211109Article in journal (Refereed)
    Abstract [en]

    Semipolar (20 (2) over bar1) plane In,Ga1-xN quantum wells (QWs) of varying alloy composition were studied by time-resolved photoluminescence. A large difference in effective radiative lifetimes. from sub-ns for x = 0.11 to similar to 30 ns for x approximate to 0.35 was found. This effect is attributed to different properties of carrier localization. In low In content QWs. recombination at extended states with short recombination times is prevalent. In QWs with a high In content, the lifetimes are increased by localization of electrons and holes at separate sites. The zigzag shape of the QW interfaces and the resulting in-plane electric field are proposed as the cause for the separate electron and hole localization.

  • 24.
    Ivanov, Ruslan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Optics and Photonics, OFO.
    Marcinkevičius, Saulius
    KTH, School of Engineering Sciences (SCI), Applied Physics, Optics and Photonics, OFO.
    Mensi, Mounir D.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Optics and Photonics, OFO.
    Martinez, Oscar
    KTH, School of Engineering Sciences (SCI), Applied Physics. GdS Optronlab, Física Materia Condensada, Universidad de Valladolid, Valladolid, Spain.
    Kuritzky, L. Y.
    Myers, D. J.
    Nakamura, S.
    Speck, J. S.
    Polarization-Resolved Near-Field Spectroscopy of Localized States in m -Plane InxGa1-x N/Ga N Quantum Wells2017In: Physical Review Applied, Vol. 7, no 6Article in journal (Refereed)
    Abstract [en]

    We present a polarization, spectrally, and spatially resolved near-field photoluminescence (PL) measurement technique and apply it to the study of wide m-plane InxGa1-xN/GaN quantum wells grown on on-axis and miscut GaN substrates. It is found that PL originates from localized states; nevertheless, its degree of linear polarization (DLP) is high with little spatial variation. This allows an unambiguous assignment of the localized states to InxGa1-xN composition-related band potential fluctuations. Spatial PL variations, occurring due to morphology features of the on-axis samples, play a secondary role compared to the variations of the alloy composition. The large PL peak wavelength difference for polarizations parallel and perpendicular to the c axis, the weak correlation between the peak PL wavelength and the DLP, and the temperature dependence of the DLP suggest that effective potential variations and the hole mass in the second valence-band level are considerably smaller than that for the first level. DLP maps for the long wavelength PL tails have revealed well-defined regions with a small DLP, which have been attributed to a partial strain relaxation around dislocations.

  • 25. Kivisto, Samuli
    et al.
    Puustinen, Janne
    Guina, Mircea
    Herda, Robert
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Dianov, Evgueny M.
    Okhotnikov, Oleg G.
    Pulse dynamics of a passively mode-locked Bi-doped fiber laser2010In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 18, no 2, p. 1041-1048Article in journal (Refereed)
    Abstract [en]

    The pulse evolution in Bi-doped soliton fiber laser with slow and fast saturable absorber has been studied both experimentally and numerically. Semiconductor saturable absorbers with balanced slow and fast absorption recovery mechanisms exhibit a bi-temporal recovery dynamics which permits both reliable start-up of passive mode-locking and short pulse generation and stabilization. The pulse dynamics within the Bi fiber laser cavity have been investigated.

  • 26. Krotkus, A.
    et al.
    Bertulis, K.
    Kaminska, M.
    Korona, K.
    Wolos, A.
    Siegert, J.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Roux, J. F.
    Coutaz, J. L.
    Be-doped low-temperature-grown GaAs material for optoelectronic switches2002In: IEE Proceedings - Optoelectronics, ISSN 1350-2433, E-ISSN 1359-7078, Vol. 149, no 3, p. 111-115Article in journal (Refereed)
    Abstract [en]

    Structural, electrical and recombination properties of Be-doped low-temperature MBE grown (LTG) GaAs have been investigated by using a number of different experimental techniques. These properties were analysed with respect to the applications of LTG GaAs in ultrafast optoelectronic devices. It has been found that a moderate Be-doping improves the structural quality of the layers and does not affect their semi-insulating behaviour. Electron and hole capture cross-sections, critical parameters for the design of optoelectronic devices from LTG GaAs, equal to sigma(n) = 1.1 x 10(-13) and sigma(p) = 1.8 x 10(-15) cm(2) were also determined.

  • 27. Leon, R.
    et al.
    Ibanez, J.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Siegert, J.
    Paskova, T.
    Monemar, B.
    Chaparro, S.
    Navarro, C.
    Johnson, S. R.
    Zhang, Y. H.
    Defect states in red-emitting InxAl1-xAs quantum dots2002In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 8Article in journal (Refereed)
    Abstract [en]

    Optical and transport measurements carried out in pn diodes and Schottky barriers containing multilayers of InAlAs quantum dots embedded in AlGaAs barriers show that while red emission from quantum dot (QD) states is obtained at similar to1.8 eV, defect states dominate the optical properties and transport in these quantum dots. These defects provide nonradiative recombination paths, which shortens the carrier lifetimes in QD's to tens of picoseconds (from similar to1 ns) and produce deep level transient spectroscopy (DLTS) peaks in both p and n type structures. DLTS experiments performed with short filling pulses and bias dependent measurements on InAlAs QD's on n-AlGaAs barriers showed that one of the peaks can be attributed to either QD/barrier interfacial defects or QD electron levels, while other peaks are attributed to defect states in both p and n type structures.

  • 28. Leon, R.
    et al.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Siegert, J.
    Cechavicius, B.
    Magness, B.
    Taylor, W.
    Lobo, C.
    Effects of proton irradiation on luminescence emission and carrier dynamics of self-assembled III-V quantum dots2002In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 49, no 6, p. 2844-2851Article in journal (Refereed)
    Abstract [en]

    The effects of proton irradiation (1.5 MeV) on photoluminescence intensities and carrier dynamics were compared between III-V quantum dots and similar quantum well structures. A significant enhancement in radiation tolerance is seen with three-dimensional (3-D) quantum confinement.. Measurements were carried out in different quantum dot (QD) structures, varying in material (InGaAs/GaAs and InAlAS/AlGaAS), QD surface density (4 x 10(8) to 3 x 10(10) cm(-2)), and substrate orientation [(100) and (311) B]. Similar trends were observed for all QD samples. A slight increase in PL emission after low to intermediate proton doses, are also observed in InGaAs/GaAs (100) QD structures. The latter is explained in terms of more efficient carrier transfer from the wetting layer via radiation-induced defects.

  • 29. Leon, Rosa
    et al.
    Chaparro, S.
    Johnson, S.R.
    Navarro, C.
    Jin, X.
    Zhang, Y.H.
    Siegert, Jörg
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Dislocation-induced spatial ordering of InAs quantum dots:  Effects on optical properties2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 9, p. 5826-5830Article in journal (Refereed)
    Abstract [en]

    Misfit dislocations were used to modify the surface morphology and to attain spatial ordering of quantum dots (QDs) by molecular beam epitaxy. Effects of anneal time and temperature on strain-relaxed InxGa1-xAs/GaAs layers and subsequent spatial ordering of InAs QDs were investigated. Photoluminescence (PL) and time-resolved PL was used to study the effects of increased QD positional ordering, increased QD uniformity, and their proximity to dislocation arrays on their optical properties. Narrower inhomogeneous PL broadening from the QDs ordered on dislocation arrays were observed, and differences in PL dynamics were found.

  • 30. Lindberg, H.
    et al.
    Sadeghi, M.
    Westlund, M.
    Wang, S. M.
    Larsson, A.
    Strassner, M.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Mode locking a 1550 nm semiconductor disk laser by using a GaInNAs saturable absorber2005In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 30, no 20, p. 2793-2795Article in journal (Refereed)
    Abstract [en]

    Passive mode locking of an optically pumped, InP-based, 1550 nm semiconductor disk laser by using a GaInNAs saturable absorber mirror is demonstrated. To reduce material heating and enable high-power operation, a 50 mu m thick diamond heat spreader is bonded to the surface of the gain chip. The laser operates at a repetition frequency of 2.97 GHz and emits near-transform-limited 3.2 ps pulses with an average output power of 120 mW.

  • 31.
    Liuolia, Vytautas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Billingsley, D.
    Sensor Elect Technol Inc, Columbia, SC USA.
    Shatalov, M.
    Sensor Elect Technol Inc, Columbia, SC USA.
    Yang, J.
    Sensor Elect Technol Inc, Columbia, SC USA.
    Gaska, R.
    Sensor Elect Technol Inc, Columbia, SC USA.
    Shur, M. S.
    Rensselaer Polytech Inst, Troy, NY, USA .
    Photoexcited carrier dynamics in AlInN/GaN heterostructures2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 24, p. 242104-Article in journal (Refereed)
    Abstract [en]

    Photoexcited carrier dynamics and localization potentials in Al0.86In0.14N/GaN heterostructures have been examined by time-resolved and scanning near-field photoluminescence (PL) spectroscopy. The large GaN and AlInN PL intensity difference, and the short AlInN PL decay and GaN PL rise times indicate efficient photoexcited hole transfer from AlInN to GaN via sub-band-gap states. These states are attributed to extended defects and In clusters. Near-field PL scans show that diameter of the localization sites and the distance between them are below 100 nm. Spatial variations of the GaN PL wavelength have been assigned to the electric field inhomogeneities at the heterostructure interface.

  • 32.
    Liuolia, Vytautas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Lin, You-Da
    Ohta, Hiroaki
    DenBaars, Steven P.
    Nakamura, Shuji
    Dynamics of polarized photoluminescence in m-plane InGaN/GaN quantum wells2010In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, no 2, p. 023101-Article in journal (Refereed)
    Abstract [en]

    Spectrally-, polarization-, and time-resolved photoluminescence (PL) experiments have been performed on 2.5 nm thick m-plane single InGaN quantum wells. It has been found that PL decay is mainly determined by nonradiative recombination through several types of recombination centers, while PL rise is largely affected by exciton transfer into localization minima. Prolonged PL rise times and time-dependent spectral shift were used to study exciton transfer into the localization centers. CharacteristiC time of the exciton transfer is 80-100 ps at lower temperatures and about 50 ps at room temperature, which corresponds to the exciton diffusion length of 200-500 nm. Degree of PL linear polarization was found to decrease at a similar rate. Decreased PL polarization for the localized excitons suggests that the localization centers are related to areas with relaxed strain. (C) 2010 American Institute of Physics. [doi:10.1063/1.3460278]

  • 33.
    Liuolia, Vytautas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Pinos, Andrea
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Gaska, R.
    Shur, M. S.
    Dynamics of carrier recombination and localization in AlGaN quantum wells studied by time-resolved transmission spectroscopy2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, no 9Article in journal (Refereed)
    Abstract [en]

    Time-resolved transmission and photoluminescence measurements were performed on Al0.35Ga0.65N/Al0.49Ga0.51N quantum well structures with different well widths. Comparison of transmission and luminescence data shows that dynamics of electrons and holes excited into extended quantum well states are governed by nonradiative recombination. For excitation into potential minima formed by band gap fluctuations, localization of electrons was observed. Excitation energy dependence of the pump-probe transient shape allows estimating localization potential, which is about 80 meV independently of the well width, and is probably caused by fluctuations of AlN molar fraction.

  • 34.
    Liuolia, Vytautas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Wang, Qin
    Andersson, Jan
    Kim, Sang-Mook
    Baek, Jong Hyeob
    Near- and far-field optical characterization of InGaN photonic crystal light emitting diodes2012In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, no 7, p. 1664-1666Article in journal (Refereed)
    Abstract [en]

    Light extraction from InGaN photonic crystal (PhC) light emitting diodes (LEDs) has been studied by scanning near-field optical microscopy and time-resolved photoluminescence. The observed patterns of the near-field intensity are complex and do not correspond to the physical structure of the photonic crystal. Comparison with conventional LEDs without the PhC showed that PhC not only improves the light extraction, but also makes the LED emission more homogeneous.

  • 35.
    Liuolia, Vytautas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Pinos, Andrea
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Lin, Y. D.
    Ohta, H.
    DenBaars, S. P.
    Nakamura, S.
    Carrier localization in m-plane InGaN/GaN quantum wells probed by scanning near field optical spectroscopy2010In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 97, no 15, p. 151106-Article in journal (Refereed)
    Abstract [en]

    Scanning near field optical microscopy (SNOM) was applied to study the carrier localization in single InGaN/GaN quantum well structures grown on nonpolar m-plane GaN substrates. Dual localization potential consisting of hundreds of nanometers- to micrometer-size areas as well as smaller localization centers were identified from the SNOM scans and near field photoluminescence spectral widths. The localization areas were found to align along the [0001] direction, which was attributed to partial strain relaxation at the monolayer steps. (C) 2010 American Institute of Physics. [doi:10.1063/1.3502482]

  • 36.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Optics.
    Dynamics of carrier transfer into In(Ga)As self-assembled quantum dots2008In: Self-Assembled Quantum Dots / [ed] Zhiming M. Wang, Springer , 2008, 1, p. 129-164Chapter in book (Refereed)
    Abstract [en]

    The chapter reviews ultrafast dynamics of carrier transfer into InAs/GaAs and InGaAs/GaAs quantum dots of different doping, densities and interlevel energies. Results from theoretical modeling and time-resolved optical studies are discussed. Considered effects include carrier transport in the barriers, capture into the dots and relaxation in the dots. Several carrier capture and relaxation mechanisms, such as longitudinal optical (LO) phonon emission, carrier-carrier scattering, capture through defect states and relaxation through barrier/wetting layer continuum states are analyzed. LO phonon-assisted capture appears to be a rather universal capture mechanism. For the carrier relaxation in doped quantum dots and/or at high carrier densities, the carrier-carrier scattering-assisted relaxation dominates. In undoped dots and low excitation levels, relaxation through LO phonon emission is found to be the relevant process. Whatever the mechanism, the carrier transfer in QD structures is, as a rule, fast, occurring in 1 to 20 ps time range.

  • 37.
    Marcinkevicius, Saulius
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Carmody, S.
    Gaarder, Andreas
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Tan, H.H.
    Jagadish, C.
    Ultrafast carrier dynamics in highly resistive InP and InGaAs produced by ion implantation2004In: ULTRAFAST PHENOMENA IN SEMICONDUCTORS AND NANOSTRUCTURE MATERIALS VIII / [ed] Tsen, KT; Song, JJ; Jiang, HX, BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING , 2004, Vol. 5352, p. 299-309Conference paper (Refereed)
    Abstract [en]

    Heavy ion implantation into InP and In0.53Ga0.47As and rapid thermal annealing has been applied to produce materials with high resistivity, good mobility and ultrashort carrier lifetime, as required for ultrafast optoelectronic applications. Two implantation methods have been analyzed: Fe+ implantation into semi-insulating InP and InGaAs, and P+ implantation into p-doped InP and InGaAs. Both approaches allow production of layers with high sheet resistance, up to 10(6) Omega/square for the P+-implanted compounds. Electron mobility in the high resistivity layers is of the order of 10(2) cm(2)V(-1)s(-1). Carrier lifetimes, measured by the time-resolved photoluminescence and reflectivity, can be tuned from similar to100 femtoseconds to tens of picoseconds by choosing implantation and annealing conditions. Measurements of carrier dynamics have shown that carrier traps act as efficient recombination centers, at least for the case of InP. The dependencies of electrical and ultrafast optical properties on the implantation dose and annealing temperature are determined by the interplay between shallow P and As antisite-related donors, deep Fe-related acceptors and defect complexes.

  • 38.
    Marcinkevicius, Saulius
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Gaarder, A.
    Leon, R.
    Rapid carrier relaxation by phonon emission in In0.6Ga0.4As/GaAs quantum dots2001In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 6411, no 11Article in journal (Refereed)
    Abstract [en]

    Carrier transfer into quantum dots has been investigated by time-resolved photoluminescence spectroscopy in a set of In0.6Ga0.4As/GaAs quantum dot structures with gradually changing interband transition and intraband level energies. Quantum dot energy levels were tuned by thermal compositional disordering of the inter-face. Time-resolved photoluminescence for low photoexcited carrier densities show efficient electron relaxation by LO phonon emission for samples in which the electron energy level separation is close to the LO phonon energy. Slower carrier transfer in samples with abrupt quantum dot/barrier interfaces is also found, the latter is attributed to strain-induced or compositional potential barriers at the quantum dot inter-face.

  • 39.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Gelzinyte, Kristina
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Ivanov, Ruslan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zhao, Yuji
    Nakamura, Shuji
    DenBaars, Steven P.
    Speck, James S.
    Spatial variations of optical properties of semipolar InGaN quantum wells2015In: Gallium Nitride Materials and Devices X, SPIE - International Society for Optical Engineering, 2015, Vol. 9363, article id 93631UConference paper (Refereed)
    Abstract [en]

    Spatial variations of band potentials and properties of carrier recombination were examined in semipolar (20 (2) over bar1) plane InGaN/GaN single quantum wells by scanning near-field photoluminescence (PL) spectroscopy. The quantum wells had In content from 0.11 to 0.36 and were emitting from violet to yellow-green. Near-field scans showed small PL peak energy and linewidth variations with standard deviations below 10 meV, which confirms small alloy composition variations in the quantum wells. The scans revealed large, similar to 5 to 10 mu m size areas of similar PL parameter values, as opposed to 100 nm scale variations, often reported for InGaN wells. With increased excitation power, an untypical photoluminescence peak energy shift to lower energies was observed. The shift was attributed to density dependent carrier redistribution between nm-scale sites of different potentials. The experimental results show that in the (20 (2) over bar1) plane InGaN quantum wells the localization potentials are shallow and the recombination properties are spatially rather uniform, which confirms the high potential of these QWs for photonic applications.

  • 40.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Gelzinyte, Kristina
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Vilnius University, Lithuania.
    Zhao, Y.
    Nakamura, S.
    DenBaars, S. P.
    Speck, J. S.
    Carrier redistribution between different potential sites in semipolar (20(2)over-bar1) InGaN quantum wells studied by near-field photoluminescence2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 11, p. 111108-Article in journal (Refereed)
    Abstract [en]

    Scanning near-field photoluminescence (PL) spectroscopy at different excitation powers was applied to study nanoscale properties of carrier localization and recombination in semipolar (20 (2) over bar1) InGaN quantum wells (QWs) emitting in violet, blue, and green-yellow spectral regions. With increased excitation power, an untypical PL peak energy shift to lower energies was observed. The shift was attributed to carrier density dependent carrier redistribution between nm-scale sites of different potentials, Near-field PL scans showed that in (20 (2) over bar1) QWs the in-plane carrier diffusion is modest, and the recombination properties arc uniform, which is advantageous for photonic applications.

  • 41.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Gushterov, A.
    Reithmaier, J. P.
    Transient electromagnetically induced transparency in self-assembled quantum dots2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 92, no 4Article in journal (Refereed)
    Abstract [en]

    A coherent absorption dip in pump-probe experiment performed on a ten layer optically thin InGaAs/GaAs quantum dot (QD) structure has been observed. Measurements performed for different wavelengths, polarizations, pulse widths, and temperatures allow assigning the dip to electromagnetically induced transparency (EIT). The EIT scheme is based on coupling of excitons with different spins in asymmetric QDs. Using spectrally narrow pulses, detrimental effect of the inhomogeneous broadening is reduced since only the QDs with transitions resonant with the pulse wavelength are addressed and participate in the EIT. The effect has been observed at temperatures up to 140 K.

  • 42.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Gusterov, A.
    Reithmaier, J. P.
    Transient electromagnetically induced transparency in InGaAs quantum dots2008In: 2008 Conference On Lasers And Electro-Optics & Quantum Electronics And Laser Science Conference: Vols 1-9, 2008, p. 3597-3598Conference paper (Refereed)
    Abstract [en]

    Electromagnetically induced transparency (EIT) based on exciton spin transitions is observed in InGaAs quantum dots. Inhomogeneous broadening of the quantum dot ensemble, detrimental for EIT, is effectively reduced by using spectrally narrow pulses.

  • 43.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Ivanov, Ruslan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Zhao, Y.
    Nakamura, S.
    DenBaars, S. P.
    Speck, J. S.
    Highly polarized photoluminescence and its dynamics in semipolar (20(2)over-bar(1)over-bar) InGaN/GaN quantum well2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, no 11, p. 111113-Article in journal (Refereed)
    Abstract [en]

    Very high polarization degree of 0.98, considerably larger than theoretical predictions, has been measured in (20 (2) over bar(1) over bar) In(0.24)Ga(0.7)6N/GaN quantum well by low temperature photoluminescence. With increasing temperature, the polarization degree decreases due to thermal population of the excited valence band level. This effect suggests an accurate method to determine the interlevel energy, which, for the studied well, is 32 meV. Time-resolved photoluminescence measurements set radiative recombination times between 2 and 12 ns for temperatures from 3 to 300 K. Nonradiative recombination was found to be slow, over 2 ns at 300 K, taking place via traps with activation energy of 0.19 eV.

  • 44.
    Marcinkevicius, Saulius
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Jagadish, C.
    Tan, H. H.
    Kaminska, M.
    Korona, K.
    Adomavicius, R.
    Krotkus, A.
    Influence of annealing on carrier dynamics in As ion-implanted epitaxially lifted-off GaAs layers2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 10, p. 1306-1308Article in journal (Refereed)
    Abstract [en]

    Electrical and dynamical optical characterization of As-ion implanted and annealed GaAs has been performed. Changes of physical properties induced by annealing have been studied in detail by using layers annealed in small steps in the temperature range 500-700 degrees C. The carrier trapping rate increases exponentially with increase of inverse annealing temperature indicating that in ion-implanted GaAs ultrafast carrier capture occurs to the same trapping centers as in low-temperature-grown GaAs. Relatively large resistivity and electron mobility in As-implanted GaAs have been observed after annealing, which shows that this material possesses properties required for a variety of ultrafast optoelectronic applications.

  • 45.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Jain, R.
    Shatalov, M.
    Yang, J.
    Shur, M.
    Gaska, R.
    High spectral uniformity of AlGaN with a high Al content evidenced by scanning near-field photoluminescence spectroscopy2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 24, p. 241108-Article in journal (Refereed)
    Abstract [en]

    Scanning near-field photoluminescence (PL) spectroscopy was applied to study spatial variations of emission spectra of AlxGa1-xN epilayers with 0.6 <= x <= 0.7. PL spectra were found to be spatially uniform with peak wavelength standard deviations of only similar to 2 meV and ratios between peak intensity standard deviations and average peak intensity values of 0.06. The observed absence of correlation between the PL peak wavelength and intensity shows that spatial distribution of nonradiative recombination centers is not related to band potential fluctuations. Our results demonstrate that the homogeneous broadening and the random cation distribution primarily determine PL line-widths for layers grown under optimized conditions.

  • 46.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Optics and Photonics, OFO.
    Kelchner, K. M.
    Kuritzky, L. Y.
    Nakamura, S.
    DenBaars, S. P.
    Speck, J. S.
    Photoexcited carrier recombination in wide m-plane InGaN/GaN quantum wells2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 11, p. 111107-Article in journal (Refereed)
    Abstract [en]

    Carrier recombination in single 10 nm wide m-plane homoepitaxial In0.15Ga0.85N/GaN quantum wells was examined by time-resolved photoluminescence. The radiative recombination time at 3.5 K was found to be short, about 0.5 ns. This value and the single-exponential luminescence decay show that the localized exciton recombination is not affected by the in-plane electric field. At room temperature, the nonradiative recombination was prevalent. The data indicate that the nonradiative recombination proceeds via efficient recombination centers. Complexes of Ga vacancies with oxygen and/or related interface defects are suggested to play this role and thus provide a direction for future improvements in materials' quality.

  • 47.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Kelchner, K. M.
    Nakamura, S.
    DenBaars, S. P.
    Speck, J. S.
    Optical properties of extended and localized states in m-plane InGaN quantum wells2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 102, no 10, p. 101102-Article in journal (Refereed)
    Abstract [en]

    Scanning near-field and time-resolved photoluminescence spectroscopy were applied to study potential fluctuations and photoexcited carrier dynamics in single m-plane InGaN quantum well structures. The far-and near-field spectra were found to have contributions from transitions to the first and second hole levels in the extended states, and transitions in the localized states. Correlations between parameters of the near-field spectra confirmed that extended state luminescence was prevailing. The localized states, which were found to be separated from the extended states by similar to 10 meV barriers, were attributed to regions of a higher In content.

  • 48.
    Marcinkevicius, Saulius
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Kelchner, Kathryn M.
    Nakamura, Shuji
    DenBaars, Steven P.
    Speck, James S.
    Optical properties and carrier dynamics in m-plane InGaN quantum wells2014Conference paper (Refereed)
    Abstract [en]

    Scanning near-field and time-resolved photoluminescence spectroscopy have been applied to characterize single m-plane InGaN QW structures. The PL spectra were found to be formed by emission from the extended and the localized states. Lateral dimensions of uniform potential regions were placed around a few tens of nm. It was shown that optimization of the template for the QW growth results in a more uniform emission spectrum and a reduced effect of carrier localization. The radiative recombination time at low temperatures was found to be short, about 0.5 ns. At room temperature, nonradiative recombination via efficient recombination centres was prevailing. Complexes of Ga vacancies with O were suggested to play this role.

  • 49.
    Marcinkevicius, Saulius
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Leon, R.
    Carrier capture and relaxation in quantum dot structures with different dot densities2000In: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. feb-51, p. 79-83Article in journal (Refereed)
    Abstract [en]

    Carrier dynamics has been measured by time-resolved photoluminescence in self-assembled InGaAs/GaAs quantum dot structures with dot density of the order of 10(8) to 10(10) cm(2). The time of carrier transfer into a dot, which is in the region from 2 to 20 PS, has been found to decrease with increasing quantum dot density. The temperature and photoexcited carrier density dependencies of the carrier transfer times suggest that potential barriers at the barrier, wetting layer and quantum dot interfaces hinder carrier capture in low-density quantum dot structures.

  • 50.
    Marcinkevicius, Saulius
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Leon, R.
    Photoexcited carrier transfer in InGaAs quantum dot structures: Dependence on the dot density2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 17, p. 2406-2408Article in journal (Refereed)
    Abstract [en]

    Carrier dynamics has been measured by time-resolved photoluminescence in self-assembled InGaAs/GaAs quantum-dot structures with dot density of the order of 10(8)-10(10) cm(-2). The time of carrier transfer into a dot, which ranges from 2 to 20 ps, has been found to decrease with increasing quantum dot density. The temperature and photoexcited carrier density dependencies of the carrier transfer times suggest that potential barriers at wetting layer and quantum-dot interfaces hinder carrier capture in low-density quantum-dot structures.

12 1 - 50 of 95
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