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Nanowire (NW) lasers operating in the near infrared spectral range are of significant technological importance for applications in telecommunications, sensing, and medical diagnostics. So far, lasing within this spectral range has been achieved using GaAs/AlGaAs, GaAs/GaAsP, and InGaAs/GaAs core/shell NWs. Another promising III-V material, not yet explored in its lasing capacity, is the dilute nitride GaNAs. In this work, we demonstrate, for the first time, optically pumped lasing from the GaNAs shell of a single GaAs/GaNAs core/shell NW. The characteristic "S"-shaped pump power dependence of the lasing intensity, with the concomitant line width narrowing, is observed, which yields a threshold gain, g(th), of 3300 cm(-1) and a spontaneous emission coupling factor beta, of 0.045. The dominant lasing peak is identified to arise from the HE21b, cavity mode, as determined from its pronounced emission polarization along the NW axis combined with theoretical calculations of lasing threshold for guided modes inside the nanowire. Even without intentional pas sivation of the NW surface, the lasing emission can be sustained up to 150 K. This is facilitated by the improved surface quality due to nitrogen incorporation, which partly suppresses the surface-related nonradiative recombination centers via nitridation. Our work therefore represents the first step toward development of room-temperature infrared NW lasers based on dilute nitrides with extended tunability in the lasing wavelength. ; Funding Agencies|Swedish Energy Agency [P40119-1]; Swedish Research Council [2015-05532]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; KAKENHI from the Japan Society for the Promotion of Science [16H05970, 23686004]; Kato Foundation for Promotion of Science; Kurata Memorial Hitachi Science and Technology Foundation; Murata Science Foundation

III-V semiconductor nanowires (NWs), such as those based on GaAs, are attractive for advanced optoelectronic and nanophotonic applications. The addition of Bi into GaAs offers a new avenue to enhance the near-infrared device performance and to add new functionalities, by utilizing the remarkable valence band structure and the giant bowing in the bandgap energy. Here, we report that alloying with Bi also induces the formation of optically-active self-assembled nanodisks caused by Bi segregation. They are located in the vicinity to the (112) corners of the GaAsBi shell and are restricted to twin planes. Furthermore, the Bi composition in the disks is found to correlate with their lateral thickness. The higher Bi composition in the disks with respect to the surrounding matrix provides a strong confinement for excitons along the NW axis, giving rise to narrow emission lines (<450 mu eV) with the predominant emission polarization orthogonal to the NW axis. Our findings, therefore, open a new possibility to fabricate self-assembled quantum structures by combining advantages of dilute bismide alloys and lattice engineering in nanowires. ; Funding Agencies|Swedish Research CouncilSwedish Research Council [2019-04312]; Swedish Foundation for International Cooperation in Research and Higher Education (STINT) [JA2014-5698]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]; KAKENHI from Japan Society of Promotion of Science [19H00855, 16H05970]

Определено, что спектральная зависимость фототока охватывает широкий интервал энергии падающих квантов от 1.07 эВ до 3 эВ. Показано, что с увеличением температуры начала кристаллизации максимумы спектральной зависимости фотоЭДС смещаются в более коротковолновую область длин волн и начало кристаллизации слоя твердогораствора (GaAs)1–x–у(Ge2)x(ZnSe)y увеличивается, время жизни фотоносителей также растет от 10−7 с при температуре начала кристаллизации Тнк=650°С до 5×10−5 с при Тнк=730°С.

Core/shell nanowire (NW) heterostructures based on III-V semiconductors and related alloys are attractive for optoelectronic and photonic applications owing to the ability to modify their electronic structure via bandgap and strain engineering. Post-growth thermal annealing of such NWs is often involved during device fabrication and can also be used to improve their optical and transport properties. However, effects of such annealing on alloy disorder and strain in core/shell NWs are not fully understood. In this work we investigate these effects in novel core/shell/shell GaAs/GaNAs/GaAs NWs grown by molecular beam epitaxy on (111) Si substrates. By employing polarization-resolved photoluminescence measurements, we show that annealing (i) improves overall alloy uniformity due to suppressed long-range fluctuations in the N composition; (ii) reduces local strain within N clusters acting as quantum dot emitters; and (iii) leads to partial relaxation of the global strain caused by the lattice mismatch between GaNAs and GaAs. Our results, therefore, underline applicability of such treatment for improving optical quality of NWs from highly-mismatched alloys. They also call for caution when using ex-situ annealing in strain-engineered NW heterostructures. ; Funding Agencies|Swedish Energy AgencySwedish Energy Agency [P40119-1]; Swedish Research CouncilSwedish Research Council [2015-05532]; Swedish Foundation for International Cooperation in Research and Higher Education (STINT) [JA2014-5698]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; KAKENHI from the Japan Society for the Promotion of ScienceMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of ScienceGrants-in-Aid for Scientific Research (KAKENHI) [16H05970, 23686004]; Kato Foundation for Promotion of Science; Kurata Memorial Hitachi Science and Technology Foundation; Murata Science Foundation; Linkoping University

Изучены структурные свойства тонкопленочных твердых растворов (GaAs)1-х(Ge2)x, выращенных методом жидкофазной эпитаксии на подложках монокристаллов GaAs. Полученные эпитаксиальные слои имели толщину 10 мкм, p-тип проводимости, удельное сопротивление 0.17 Омсм. Морфологические исследования с помощью атомно-силовой микроскопии (АСМ) показали, что наблюдаемые на поверхности эпитаксиальных слоев (GaAs)1-х(Ge2)x наноконусы обусловлены присутствием в них атомов Ge. Спектры фоточуствительности этих твердых растворов имеют своеобразные флуктуации, обусловленные образованием в них различных комплексов заряженных ионов атомов составляющих компонентов. Анализ спектров фоточувствительности гетероструктур n-GaAs-p- (GaAs)1-х(Ge2)x с помощью программы Wolfram Mathematics 7 показал, что спектр состоит из трех пиков, обусловленных соединениями As-Ge, Gе-Ge и Ga-Ge.

Inhalt dieses Buches ist die detaillierte Charakterisierung der Oberfläche von GaAs-Halbleitern hinsichtlich oberflächennaher Verunreinigungen und passivierender Oxidschichten. Der Autor entwickelt ein Verfahren zum quantitativen Nachweis von metallischen Spurenelementen mit der Flugzeit-Sekundärionenmassenspektrometrie (TOF-SIMS), das es möglich macht, Oberflächenbelegungen auf GaAs mit Konzentrationen kleiner 109 Atome/cm2 quantitativ nachzuweisen. Ein Vergleich passivierender Oxide hinsichtlich ihrer Komponenten, Schichtstruktur und Dicke liefert die Grundlagen für gezielte Änderungen des Herstellungsprozesses

We investigate inelastic light scattering by longitudinal optic phonon-plasmon coupled modes LOPCMs in a series of heavily Se-doped, n-type GaAs1−xNx epilayers with x 0.4%. We perform a line shape analysis of the LOPCM spectra to estimate the optical effective mass, mopt , and the scattering time of the conduction electrons in GaAsN. We use these results to evaluate an effective carrier mobility for our samples. The values thus obtained, which we compare with measured electron Hall mobilities, indicate that the x-dependence of the mobility in GaAs1−xNx is dominated by the scattering time, rather than by the variation of the electron effective mass. The Raman analysis yields mopt values that are lower than those obtained from the band anticrossing model. © 2008 American Institute of Physics. ; This work is supported by the Spanish Government Projects MAT 2004-0664 and MAT2007-63617, and Ramon y Cajal Program and the EPSRC, United Kingdom. 1M. Henini, Dilute Nitride Semiconductors Elsevier Science, Amsterdam ; Peer reviewed

Обнаружено, что прямая ветвь вольтамперной характеристики (ВАХ) гетероструктур n-GaAs-р-(GaAs)1−x−y(Ge2)x(ZnSe)y имеет участок сублинейного роста тока с напряжением типа V=V0exp(Jad). Оценены концентрации глубоких примесей, ответственных за появление сублинейного участка вольтамперной характеристики. Экспериментальные результаты объясняются на основе теории эффекта инжекционного обеднения. Показано, что подвижность основных носителей уменьшается, а неосновных носителей увеличивается с ростом температуры.

Spectrum region of millimeter wave is extensively used in various areas: from consumer devices in telecommunication networks, to specific applications in military and diagnostic medicine. Schottky diode is the most commonly used two terminal device in microwave receivers. Although the operational frequency of Schottky diode is reaching the terahertz frequency range it has several drawbacks such as sensitivity dependence on temperature, long-term instability and sensitivity to overloads. These drawbacks impelled one to search new type of devices. Two types of microwave diodes fabricated using GaAs/AlGaAs heterostructures are presented in the thesis. The quality of semiconductor epitaxial layers was experimentally estimated using photoluminescence and time correlated single photon counting techniques. The process of microwave diode fabrication is described. Electrical properties of microwave diodes were estimated from current-voltage characteristics and properties of microwaves detection were investigated in wide frequency range.

Spectrum region of millimeter wave is extensively used in various areas: from consumer devices in telecommunication networks, to specific applications in military and diagnostic medicine. Schottky diode is the most commonly used two terminal device in microwave receivers. Although the operational frequency of Schottky diode is reaching the terahertz frequency range it has several drawbacks such as sensitivity dependence on temperature, long-term instability and sensitivity to overloads. These drawbacks impelled one to search new type of devices. Two types of microwave diodes fabricated using GaAs/AlGaAs heterostructures are presented in the thesis. The quality of semiconductor epitaxial layers was experimentally estimated using photoluminescence and time correlated single photon counting techniques. The process of microwave diode fabrication is described. Electrical properties of microwave diodes were estimated from current-voltage characteristics and properties of microwaves detection were investigated in wide frequency range.

Spectrum region of millimeter wave is extensively used in various areas: from consumer devices in telecommunication networks, to specific applications in military and diagnostic medicine. Schottky diode is the most commonly used two terminal device in microwave receivers. Although the operational frequency of Schottky diode is reaching the terahertz frequency range it has several drawbacks such as sensitivity dependence on temperature, long-term instability and sensitivity to overloads. These drawbacks impelled one to search new type of devices. Two types of microwave diodes fabricated using GaAs/AlGaAs heterostructures are presented in the thesis. The quality of semiconductor epitaxial layers was experimentally estimated using photoluminescence and time correlated single photon counting techniques. The process of microwave diode fabrication is described. Electrical properties of microwave diodes were estimated from current-voltage characteristics and properties of microwaves detection were investigated in wide frequency range.

Spectrum region of millimeter wave is extensively used in various areas: from consumer devices in telecommunication networks, to specific applications in military and diagnostic medicine. Schottky diode is the most commonly used two terminal device in microwave receivers. Although the operational frequency of Schottky diode is reaching the terahertz frequency range it has several drawbacks such as sensitivity dependence on temperature, long-term instability and sensitivity to overloads. These drawbacks impelled one to search new type of devices. Two types of microwave diodes fabricated using GaAs/AlGaAs heterostructures are presented in the thesis. The quality of semiconductor epitaxial layers was experimentally estimated using photoluminescence and time correlated single photon counting techniques. The process of microwave diode fabrication is described. Electrical properties of microwave diodes were estimated from current-voltage characteristics and properties of microwaves detection were investigated in wide frequency range.