Auger recombination in GaAs and GaSb

Benz, G.; Conradt, R.

doi:10.1103/physrevb.16.843

Cited by 122 publications

(47 citation statements)

References 31 publications

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“…15 However, the origin of this transition has not been clearly resolved until now. 16 The above-band-gap peak at 830 meV is an (e,h) transition including tail states and shallow acceptors 17 and is observed here due to high excitation intensities in CL.…”

mentioning

confidence: 68%

Cathodoluminescence studies of growth and process-induced defects in bulk gallium antimonide

Méndez

Dutta

Piqueras

et al. 1995

Applied Physics Letters

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The homogeneity and luminescence properties of undoped bulk GaSb have been studied by the cathodoluminescence ͑CL͒ technique in the scanning electron microscope. CL images have revealed a nonuniform distribution of native defects in GaSb wafers prepared from as-grown single crystals. Postgrowth annealing in vacuum, gallium, and antimony atmospheres has been performed to obtain more accurate information about the defect structure in this material. In general, on annealing, homogeneous distribution of impurities is observed throughout the wafers. CL spectra show that a luminescence band ͑centered at 756 meV͒ is enhanced by annealing in a gallium atmosphere, suggesting that Ga atoms play an important role in the formation of this acceptor center. The 756 meV peak has been attributed to a transition from conduction band to an acceptor center comprised of Ga Sb or a related complex. Interestingly, localized crystallization at the subgrain boundaries seems to occur by annealing in Ga atmosphere. © 1995 American Institute of Physics.Recently, ZrF 4 -based fluoride glass optical fibers have been predicted to have intrinsic minimum losses one or two orders of magnitude lower than those of conventional silica fibers.1 The loss minima for the next generation fibers are expected to occur in the 2-4 m wavelength regime. These estimations have stimulated considerable interest on materials for mid-IR sources and detectors. GaSb is the most suitable substrate material for various lattice-matched optoelectronic devices in the range of 0.3 eV ͑InGaAsSb͒-1.58 eV ͑AlGaAsSb͒.2-4 There are several reports on the growth of bulk GaSb single crystals employing various techniques.5-7 However, there are very few reports on the characterization of defects in the grown crystals. For defect characterization, the cathodoluminescence ͑CL͒ technique has been found to be highly sensitive and is extensively used for the spatial defect mapping. To the best of our knowledge, CL microscopy has not been applied to defects studied in GaSb. In this letter, we present the results of CL investigation of defects in bulk GaSb generated during growth and postgrowth annealing treatments.The GaSb samples used in our studies were vertical Bridgman grown single crystals.8 Undoped GaSb is always p type in nature with the acceptor concentration of approximately 10 17 cm Ϫ3 at room temperature. The acceptor is intrinsic and is due to a vacant gallium site (V Ga ) and gallium antisite (Ga Sb ). The acceptor concentration can be reduced either by nonstoichiometric melt growth or by employing low-temperature growth techniques. 9,10 In this work we have performed postgrowth annealing in vacuum, gallium, and antimony atmospheres to examine the evolution and nature of the native acceptors. The wafers were prepared by conventional chemomechanical polishing. Prior to annealing, the samples were etched in CH 3 COOH:HNO 3 :HF ͑20:9:1͒ to remove any damaged layer left behind after polishing, dipped in HCl, and rinsed in methanol. Thermal annealing of the samples was carried ...

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mentioning

confidence: 68%

Cathodoluminescence studies of growth and process-induced defects in bulk gallium antimonide

Méndez

Dutta

Piqueras

et al. 1995

Applied Physics Letters

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“…Like in conventional semiconductors, strong optical excitation results in a population-inverted state [15][16][17][18][19][20]. On the other hand, photo-generated electron-hole pairs in a conventional semiconductor typically relax by Auger recombination [21][22][23][24], a process that is strongly suppressed in photo-excited graphene due to the abence of occupied states at the bottom of the conduction band. Hence, in contrast to conventional semiconductors, primary thermalization events in graphene are dominated by impact ionization [25][26][27][28], where the excess energy of the photo-excited electron is used to generate additional electron-hole pairs.…”

Section: Introductionmentioning

confidence: 99%

Probing carrier dynamics in photo-excited graphene with time-resolved ARPES

Gierz

2017

Journal of Electron Spectroscopy and Related Phenomena

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The dynamics of photo-generated electron-hole pairs in solids are dictated by many-body interactions such as electron-electron and electron-phonon scattering. Hence, understanding and controlling these scattering channels is crucial for many optoelectronic applications, ranging from light harvesting to optical amplification. Here we measure the formation and relaxation of the photo-generated non-thermal carrier distribution in monolayer graphene with time-and angleresolved photoemission spectroscopy. Using sub 10fs pulses we identify impact ionization as the primary scattering channel, which dominates the dynamics for the first 25fs after photo-excitation.Auger recombination is found to set in once the carriers have accumulated at the Dirac point with time scales between 100 and 250fs, depending on the number of non-thermal carriers. Our observations help in gauging graphene's potential as a solar cell and TeraHertz lasing material.

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“…Moreover, several near-band-edge excitonic peaks in the range of 792-808 meV and a peak at 717 meV corresponding to an exciton bound to the ionized native acceptor appear. Various peaks appearing in the PL spectrum of bulk GaSb have been assigned earlier 18,20 and are given in Table I. For the sake of completeness, the peaks observed in CL spectra discussed in the previous section are also listed.…”

Section: Photoluminescence Spectramentioning

confidence: 99%

“…The broad spectrum for the unpassivated sample ͓spectrum ͑i͔͒ has been deconvoluted into four main peaks at 704, 775, 805, and 830 meV. The above-band-gap peak at 830 meV is an ͑e,h͒ transition including tail states and shallow acceptors 18 arising due to high excitation intensities in CL. The 805 meV is the band-gap-related peak.…”

Section: B Cathodoluminescence Spectramentioning

confidence: 99%

Passivation of surface and bulk defects in p -GaSb by hydrogenated amorphous silicon treatment

Dutta

Sreedhar

Bhat

et al. 1996

Journal of Applied Physics

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Passivation of point and extended defects in GaSb has been observed as a result of hydrogenated amorphous silicon ͑a-Si:H͒ treatment by the glow discharge technique. Cathodoluminescence ͑CL͒ images recorded at various depths in the samples clearly show passivation of defects on the surface as well as in the bulk region. The passivation of various recombination centers in the bulk is attributed to the formation of hydrogen-impurity complexes by diffusion of hydrogen ions from the plasma. a-Si:H acts as a protective cap layer and prevents surface degradation which is usually encountered by bare exposure to hydrogen plasma. An enhancement in luminescence intensity up to 20 times is seen due to the passivation of nonradiative recombination centers. The passivation efficiency is found to improve with an increase in a-Si:H deposition temperature. The relative passivation efficiency of donors and acceptors by hydrogen in undoped and Te-compensated p-GaSb has been evaluated by CL and by the temperature dependence of photoluminescence intensities. Most notably, effective passivation of minority dopants in tellurium compensated p-GaSb is evidenced for the first time.

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Auger recombination in GaAs and GaSb

Cited by 122 publications

References 31 publications

Cathodoluminescence studies of growth and process-induced defects in bulk gallium antimonide

Cathodoluminescence studies of growth and process-induced defects in bulk gallium antimonide

Probing carrier dynamics in photo-excited graphene with time-resolved ARPES

Passivation of surface and bulk defects in p -GaSb by hydrogenated amorphous silicon treatment

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