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  • 1.
    Gustafsson, Oscar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ekenberg, Ulf
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101).
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Höglund, L.
    Karim, A.
    Noharet, B.
    Wang, Q.
    Gromov, A.
    Almqvist, S.
    Zhang, A.
    Acreo, Sweden.
    Junique, S.
    Andersson, J. Y.
    Asplund, C.
    von Würtemberg, R. Marcks
    Malm, H.
    Martijn, H.
    Long-wavelength infrared quantum-dot based interband photodetectors2011Ingår i: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 54, nr 3, s. 287-291Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits including long carrier lifetime due to the type-II band alignment, suppressed Shockley-Read-Hall generation-recombination due to the relatively large-bandgap matrix material, inhibited Auger recombination processes due to the tensile strain and epitaxial simplicity. Metal-organic vapor-phase epitaxy was used to grow multiple (Al)GaAs(Sb) QD layers on InAs substrates at different QD nominal thicknesses, compositions, doping conditions and multilayer periods, and the material was characterized using atomic force and transmission electron microscopy, and Fourier-transform infrared absorption spectroscopy. Dot densities up to 1 x 10(11) cm(-2), 1 x 10(12) cm(-2) and 3 x 10(10) cm(-2) were measured for GaAs, AlGaAs and GaAsSb QDs, respectively. Strong absorption in GaAs, AlGaAs and GaAsSb multilayer QD samples was observed in the wavelength range 6-12 mu m. From the wavelength shift in the spectral absorption for samples with varying QD thickness and composition it is believed that the absorption is due to an intra- valance band transition. From this it is possible to estimate the type-II inter-band transition wavelength, thereby suggesting that (Al)GaAs(Sb) QD/InAs heterostructures are suitable candidates for LWIR detection and imaging.

  • 2.
    Marcks von Würtemberg, Rickard
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    A novel electrical and optical confinement scheme for surface emitting optoelectronic devices2006Ingår i: WORKSHOP ON OPTICAL COMPONENTS FOR BROADBAND COMMUNICATION / [ed] Fonjallaz, PY; Pearsall, TP, BELLINGHAM, WA: SPIE-INT SOC OPTICAL ENGINEERING , 2006, Vol. 6350, s. 63500J-1-63500J-10Konferensbidrag (Refereegranskat)
    Abstract [en]

    A novel electrical and optical confinement scheme for surface emitting optoelectronic devices is presented. The scheme is based on epitaxial regrowth of a pnp current blocking layer structure around a mesa etched in the vertical cavity region of the device. The lateral size and orientation of the mesa is defined lithographically and dry etching is used to create vertical mesa sidewalls. By orienting the mesa sidewalls in certain crystallographic directions, it is possible to selectively grow a current blocking pnp layer structure on the exposed n-type lower cladding layer of the cavity whithout obstructing the electrical injection into the active region. The concept is evaluated in 1.2-mu m GaAs-based light emitting diodes with InGaAs quantum wells. This type of structure can easily be used as the amplifying region of a vertical cavity laser, providing a good alternative to selective oxidation confinement.

  • 3. Reshanov, Sergey A.
    et al.
    Schöner, Adolf
    Kaplan, Wlodek
    Zhang, Andy
    Lim, Jang-Kwon
    Bakowski, Mietek
    Full Epitaxial Trench Type Buried Grid SiC JBS Diodes2014Ingår i: ECS Transactions, ISSN 1938-5862, E-ISSN 1938-6737, Vol. 64, nr 7, s. 289-293Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper presents the advanced concept of fully epitaxial SiC junction barrier Schottky (JBS) diodes. It combines trench etching with embedded epitaxial re-growth and enables cost-efficient manufacturing. Fabricated devices are rated for 20A / 1200V and have leakage currents below 0.1µA at 1000V blocking voltage.

  • 4. Söderberg, E.
    et al.
    Gustavsson, J. S.
    Modh, P.
    Larsson, A.
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Transmission Experiments using 1.3 um Single Mode InGaAs VCSELs2007Ingår i: The European Conference on Lasers and Electro-Optics (CLEO_Europe) 2007, Optical Society of America, 2007Konferensbidrag (Refereegranskat)
  • 5. Söderberg, E.
    et al.
    Gustavsson, J. S.
    Modh, P.
    Larsson, A.
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Transmission experiments using 1.3 ÎŒn single mode InGaAs VCSELs2007Ingår i: Conference on Lasers and Electro-Optics Europe - Technical Digest, 2007Konferensbidrag (Refereegranskat)
  • 6. Söderberg, E.
    et al.
    Modh, P.
    Gustavsson, J. S.
    Larsson, A.
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Single mode 1.28 ÎŒm InGaAs VCSELs using an inverted surface relief2006Ingår i: Conference Digest - IEEE International Semiconductor Laser Conference, 2006, s. 123-124Konferensbidrag (Refereegranskat)
    Abstract [en]

    High performance 1.28 Όm InGaAs single mode VCSELs have been fabricated using an inverted surface relief to relax critical fabrication tolerances. Higher order mode suppression >30 dB and 10 Gbps modulation are demonstrated up to 85°C.

  • 7. Söderberg, E.
    et al.
    Modh, P.
    Gustavsson, J.S.
    Larsson, A.
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    High speed, high temperature operation of 1.28-μm singlemode InGaAs VCSELs2006Ingår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 42, nr 17, s. 978-979Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Singlemode 1.28 μm InGaAs VCSELs, with a higher-order mode suppression >30 dB in the temperature range 25-85°C, have been fabricated using an inverted surface relief technique for relaxed fabrication tolerances. High performance 2.5 and 10 Gbit/s modulation is demonstrated in the same temperature range.

  • 8. Söderberg, Emma
    et al.
    Gustavsson, Johan S.
    Modh, Peter
    Larsson, Anders
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    High-temperature dynamics, high-speed modulation, and transmission experiments using 1.3-mu m InGaAs single-mode VCSELs2007Ingår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 25, nr 9, s. 2791-2798Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-temperature dynamics, including small and large signal modulation response, of 1.28-ftm GaAs-based vertical-cavity surface-emitting lasers (VCSELs) with highly strained InGaAs quantum wells have been investigated. The VCSELs are oxide-confined with a relatively large oxide aperture for high output power and have a surface relief for fundamental mode operation. An inverted surface relief is used to improve manufacturability and to suppress oxide modes that otherwise appear in VCSELs with a large detuning, between the cavity resonance and the gain peak. The size dependence of the modulation bandwidth and bandwidth limitations are. investigated. A VCSEL with an optimum combination of oxide aperture and surface relief diameters produces clear open eyes with an extinction ratio of > 6 dB at OC-48 and 10-GbE bit rates from 25 degrees C to 85 degrees C under constant drive conditions. The same VCSEL is also shown to be capable of eiror-free transmission (BER < 10(-9)) over 9 km of standard single-mode fiber under the same conditions.

  • 9. Wang, Qin
    et al.
    Li, Xun
    Zhang, Andy
    Acreo, Sweden.
    Almqvist, Susanne
    Karim, Amir
    Noharet, Bertrand
    Andersson, Jan Y.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Yu, Shun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Gustafsson, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Asplund, Carl
    Gothelid, Emmanuelle
    Analysis of surface oxides on narrow bandgap III-V semiconductors leading towards surface leakage free IR photodetectors2012Ingår i: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 8353, s. 835311-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Narrow bandgap semiconductors GaSb, InAs, and InSb are important building blocks for infrared photodetectors based on type-II InSb quantum dots or an InAs/GaSb strained layer superlattice. Understanding the surface chemical composition of these materials can provide valuable information that enables optimization of device surface passivation techniques leading towards surface leakage free IR photodetectors. We report on an investigation into Ga-, In-, Sb-, and As-oxides and other chemical species on the surface of untreated, dry etched and thermally treated GaSb, InAs and InSb samples by x-ray photoelectron spectroscopy. The experimental results reveal the presence of Sb- and Ga-oxides on the surfaces of the untreated and treated GaSb samples. Both Sb- and In-oxides were observed on the surface of all InSb samples, and especially the dry etched sample had thicker oxide layers. In the case of the InAs samples, not only In-and As-oxides XPS signals were obtained, but also AsCl species were found on the ICP dry etched sample. These results helped to analyze the dark current of our fabricated IR detectors.

  • 10. Westbergh, P.
    et al.
    Söderberg, E.
    Gustavsson, J. S.
    Modh, P.
    Larsson, A.
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Single mode 1.3 ÎŒm InGaAs VCSELs for access network applications2008Ingår i: Semiconductor Lasers and Laser Dynamics III, 2008, Vol. 6997Konferensbidrag (Refereegranskat)
    Abstract [en]

    GaAs-based VCSELs emitting near 1.3 Όm are realized using highly strained InGaAs quantum wells and a large detuning of the cavity resonance with respect to the gain peak. The VCSELs have an oxide aperture for current and optical confinement and an inverted surface relief for suppression of higher-order transverse modes. The inverted surface relief structure also has the advantage of suppressing oxide modes that otherwise appear in VCSELs with a large detuning between the cavity resonance and the gain peak. Under large signal, digital modulation, clear and open eyes and error free transmission over 9 km of single mode fiber have been demonstrated at the OC-48 and 10 GbE bit rates up to 85°C. Here we review these results and present results from a complementary study of the RF modulation characteristics, including second order harmonic and third order intermodulation distortion, relative intensity noise (RIN), and spurious free dynamic range (SFDR). RIN levels comparable to those of single mode VCSELs emitting at 850 nm are demonstrated, with values from -140 to -150 dB/Hz. SFDR values of 100 and 95 dB·Hz2/3 were obtained at 2 and 5 GHz, respectively, which is in the range of those required in radio-over-fiber systems.

  • 11. Zhang, Andy Zhenzhong
    et al.
    Reshanov, Sergey A.
    Schöner, Adolf
    Kaplan, Wlodek
    Kwietniewski, N.
    Lim, Jang-Kwon
    Bakowski, Mietek
    Planarization of epitaxial SiC trench structures by plasma ion etchingManuskript (preprint) (Övrigt vetenskapligt)
  • 12.
    Zhang, Andy Zhenzhong
    et al.
    Acreo, Sweden .
    Wang, Qin
    Karlsson, Stefan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101). Kista Photonics Resarch Center, Sweden.
    Kjebon, Olle
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101). Kista Photonics Resarch Center, Sweden.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101). Kista Photonics Resarch Center, Sweden.
    Fonjallaz, Pierre-Yves
    Almqvist, Susanne
    Chacinski, Marek
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101).
    Thylen, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101). Kista Photonics Resarch Center, Sweden.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Honecker, Joerg
    Steffan, Andreas
    Fabrication of an electro-absorption transceiver with a monolithically integrated optical amplifier for fiber transmission of 40-60 GHz radio signals2011Ingår i: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 26, nr 1, s. 014042-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the fabrication of a monolithically integrated semiconductor optical amplifier (SOA) and a reflective electro-absorption transceiver (EAT) for 40-60 GHz radio-over-fiber applications. The EAT can either function as a transmitter (reflective modulator) or as a receiver (photodetector) depending on operation mode. The SOA and the EAT sections are based on different InGaAsP multiple quantum-well active layers connected by a butt joint. Benzocyclobutene is used to reduce the capacitance beside the ridge mesa. Devices are designed to have a peaked response at the operating frequency through the design of microwave waveguides on top of the devices. The packaged device exhibits at 0.1 mW optical input power an amplified DC responsivity of 18.5 mA mW(-1) and a modulation efficiency of 0.67 mW V-1. The estimated radio frequency loss at 40 GHz of an optical link consisting of two SOA-EAT devices was 23 dB using an unmodulated optical input carrier to the transmitter of 0.94 mW.

  • 13.
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Epitaxial growth optimization for 1.3-um InGaAs/GaAs Vertical-Cavity Surface-Emitting lasers2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Long-wavelength (1.3-μm) vertical-cavity surface-emitting lasers (VCSELs) are of great interest as low-cost, high performance light sources for fiber-optic metro and access networks. During recent years the main development effort in this field has been directed towards all epitaxial GaAs-based structures by employing novel active materials. Different active region candidates for GaAs-based 1.3-μm VCSELs such as GaInNAs/GaAs QWs, GaAsSb QWs or InAs/InGaAs QDs have been investigated. However, the difficult growth and materials properties of these systems have so far hampered any real deployment of the technology. More recently, a new variety of VCSELs have been developed at KTH as based on highly strained InGaAs QWs and negative gain cavity detuning to reach the 1.3-μm wavelength window. The great benefit of this approach is that it is fully compatible with standard materials and processing methods.

    The aim of this thesis is to investigate long-wavelength (1.3-μm) VCSELs using ~1.2-μm In0.4GaAs/GaAs Multiple Quantum Wells (MQWs). A series of QW structures, DBR structures and laser structures, including VCSELs and Broad Area lasers (BALs) were grown by metal-organic vapor phase epitaxy (MOVPE) and characterized by various techniques: Photoluminescence (PL), high-resolution x-ray diffraction (XRD), atomic force microscopy (AFM), high accuracy reflectance measurements as well as static and dynamic device characterization. The work can be divided into three parts. The first part is dedicated to the optimization and characterization of InGaAs/GaAs QWs growth for long wavelength and strong luminescence. A strong sensitivity to the detailed growth conditions, such as V/III ratio and substrate misorientation is noted. Dislocations in highly strained InGaAs QW structure and Sb as surfactant assisted in InGaAs QW growth are also discussed here. The second part is related to the AlGaAs/GaAs DBR structures. It is shown that the InGaAs VCSELs with doped bottom DBRs have significantly lower slope efficiency, output power and higher threshold current. By a direct study of buried AlGaAs/GaAs interfaces, this is suggested to be due to doping-enhanced Al-Ga hetero-interdiffusion. In the third part, singlemode, high-performance 1.3-μm VCSELs based on highly strained InGaAs QWs are demonstrated. Temperature stable singlemode performance, including mW-range output power and 10 Gbps data transmission, is obtained by an inverted surface relief technique.

  • 14.
    Zhang, Zhenzhong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Materials and Processing Technologies for Advanced Electronic and Photonic Devices2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 15.
    Zhang, Zhenzhong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    On the long-wavelength optimization of highly strained InGaAs/GaAs quantum wells grown by metal-organic vapor-phase epitaxy2008Ingår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 310, nr 13, s. 3163-3167Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have investigated the influence of the metal-organic vapor-phase epitaxy growth conditions on the long-wavelength optimization of InGaAs/GaAs quantum wells (QWs). It is found that the V/III ratio is a critical parameter for the in incorporation and wavelength extension, with a strong sensitivity even at very high values. Furthermore, it is noted that the exact crystallographic substrate surface orientation close to (001) may have a strong influence on the photoluminescence (PL) properties with a maximum PL wavelength for orientations within 0.01-0.03 degrees from (0 0 1). This is discussed in terms of changing interface morphology and growth modes with increasing misorientation. Finally, the application of antimony as surfactant is not found to have an improving effect on the layer integrity, whereas a slight extension of the emission wavelength indicates a small incorporation of antimony in the QWs.

  • 16.
    Zhang, Zhenzhong
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Marcks von Würtemberg, Rickard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Optical loss and interface morphology in AlGaAs/GaAs distributed Bragg reflectors2007Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, nr 10, s. 101101-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is shown that n-type doping of AlGaAs/GaAs distributed Bragg reflectors (DBRs) grown by metal-organic vapor-phase epitaxy has a profound negative impact on the performance of vertical-cavity surface-emitting lasers (VCSELs) based on such mirrors. Using an intracavity contact scheme, 1.3-mu m-range InGaAs VCSELs with and without doping in the bottom DBR are directly compared. Doped mirrors lead to lower slope efficiency, lower output power, and higher threshold current. From x-ray diffraction, high-accuracy reflectance measurements, and atomic force microscopy studies, it is suggested that this performance degradation is due to the doping-enhanced Al-Ga interdiffusion, leading to interface roughening and increased scattering loss.

1 - 16 av 16
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