Gallium vacancy and the residual acceptor in undoped GaSb studied by positron lifetime spectroscopy and photoluminescence
TL;DR: In this article, annealing studies were performed to study undoped p-type gallium antimonide materials and a 314 ps positron lifetime component was attributed to Ga vacancy (V-Ga) related defect.
Abstract: Positron lifetime, photoluminescence (PL), and Hall measurements were performed to study undoped p-type gallium antimonide materials. A 314 ps positron lifetime component was attributed to Ga vacancy (V-Ga) related defect. Isochronal annealing studies showed at 300 degreesC annealing, the 314 ps positron lifetime component and the two observed PL signals (777 and 797 meV) disappeared, which gave clear and strong evidence for their correlation. However, the hole concentration (similar to2x10(17) cm(-3)) was observed to be independent of the annealing temperature. Although the residual acceptor is generally related to the V-Ga defect, at least for cases with annealing temperatures above 300 degreesC, V-Ga is not the acceptor responsible for the p-type conduction. (C) 2002 American Institute of Physics.
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TL;DR: In this article, acceptor-type defects in GaSb1−xBix grown by molecular beam epitaxy were studied and it was shown that both Ga vacancies and Ga antisites contribute to the hole density and the proportion of the two acceptor type defects vary in the layers.
Abstract: We study acceptor-type defects in GaSb1−xBix grown by molecular beam epitaxy. The hole density of the GaSb1−xBix layers, from capacitance-voltage measurements of Schottky diodes, is higher than that of the binary alloys and increases linearly up to 1019 − cm 3 with the Bi content. Positron annihilation spectroscopy and ab initio calculations show that both Ga vacancies and Ga antisites contribute to the hole density and that the proportion of the two acceptor-type defects vary in the layers. The modification of the band gap due to Bi incorporation as well as the growth parameters are suggested to affect the concentrations of acceptor-type defects.
13 citations
TL;DR: In this paper, electron irradiated undoped liquid encapsulated Czochralski (LEC) grown GaSb samples were studied by positron lifetime spectroscopy (PLS) and photoluminescence (PL).
Abstract: Electron irradiated undoped liquid encapsulated Czochralski (LEC) grown GaSb samples were studied by positron lifetime spectroscopy (PLS) and photoluminescence (PL). In addition t ot he 315 ps component reported in the previous studies, another defect with a lifetime of 280 ps was also identified in the present electron irradiated samples. The bulk lifetime of the GaSb material was found to be 258 ps. The VGa,280 ps and the VGa,315 ps defects were associated with two independent Ga vacancy related defects having different microstructures. The well known 777 meV PL signal (usually band A) was also observed in the electron irradiated undoped GaSb samples. The band A intensity decreases with increasing electron irradiation dosage and it disappears after the 300 ◦ Ca nnealing regardless of the irradiation dosage. The origin of the band A signal is also discussed.
11 citations
TL;DR: In this paper, the effect of growth conditions on the point defect balance in GaSb:Bi epitaxial layers grown by molecular beam epitaxy was analyzed using density functional theory and compared to experimental results.
Abstract: Positron annihilation spectroscopy in both conventional and coincidence Doppler broadening mode is used for studying the effect of growth conditions on the point defect balance in GaSb:Bi epitaxial layers grown by molecular beam epitaxy. Positron annihilation characteristics in GaSb are also calculated using density functional theory and compared to experimental results. We conclude that while the main positron trapping defect in bulk samples is the Ga antisite, the Ga vacancy is the most prominent trap in the samples grown by molecular beam epitaxy. The results suggest that the p–type conductivity is caused by different defects in GaSb grown with different methods.
10 citations
TL;DR: In this article, a shallow acceptor having an ionization energy of 32 meV was found to be the important residual acceptor associated with the p-type conduction of the undoped GaSb material.
Abstract: Liquid encapsulated Czochralski grown undoped p-type GaSb samples were studied by temperature-dependent Hall measurement A shallow acceptor having an ionization energy of 32 meV was found to be the important residual acceptor associated with the p-type conduction of the undoped GaSb material The carrier mobility data were fitted well by the relaxation time approximation model involving various carrier scattering processes Other than the typical important scattering processes in limiting the carrier mobility in III-V semiconductors (ie ionized impurity, acoustic phonon, polar optical phonon and non-polar optical phonon), vacancy scattering has to be included so as to give a good fit to the experimental data The concentrations of the vacancy and the 32 meV acceptor in the electron irradiated samples were found to increase significantly upon annealing, but such increase was not found in the non-irradiated sample
8 citations
TL;DR: In this article , a series of Ca3Ga4O9: Bi3+, Zn2+ phosphors synthesized via a high temperature solid-state reaction were analyzed and the influence of Zn 2+ ions on both structure and luminescence properties were reported.
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919 citations
TL;DR: The 3-V ternaries and quaternaries (AlGaIn)(AsSb) lattice matched to GaSb is a promising material for high speed electronic and long wavelength photonic devices.
Abstract: Recent advances in nonsilica fiber technology have prompted the development of suitable materials for devices operating beyond 155 mu m The III-V ternaries and quaternaries (AlGaIn)(AsSb) lattice matched to GaSb seem to be the obvious choice and have turned out to be promising candidates for high speed electronic and long wavelength photonic devices Consequently, there has been tremendous upthrust in research activities of GaSb-based systems As a matter of fact, this compound has proved to be an interesting material for both basic and applied research At present, GaSb technology is in its infancy and considerable research has to be carried out before it can be employed for large scale device fabrication This article presents an up to date comprehensive account of research carried out hitherto It explores in detail the material aspects of GaSb starting from crystal growth in bulk and epitaxial form, post growth material processing to device feasibility An overview of the lattice, electronic, transport, optical and device related properties is presented Some of the current areas of research and development have been critically reviewed and their significance for both understanding the basic physics as well as for device applications are addressed These include the role of defects and impurities on the structural, optical and electrical properties of the material, various techniques employed for surface and bulk defect passivation and their effect on the device characteristics, development of novel device structures, etc Several avenues where further work is required in order to upgrade this III-V compound for optoelectronic devices are listed It is concluded that the present day knowledge in this material system is sufficient to understand the basic properties and what should be more vigorously pursued is their implementation for device fabrication (C) 1997 American Institute of Physics
655 citations
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01 Jan 2003
TL;DR: In this article, the authors compare Positron annihilation with other defect-sensitive techniques, such as defect characterisation in III-V and II-VI compounds, and compare them with other techniques.
Abstract: 1 Introduction.- 2 Experimental Techniques.- 3 Basics of Positron Annihilation in Semiconductors.- 4 Defect Characterization in Elemental Semiconductors.- 5 Defect Characterization in III-V Compounds.- 6 Defect Characterization in II-VI Compounds.- 7 Defect Characterization in Other Compounds.- 8 Applications of Positron Annihilation in Defect Engineering.- 9 Comparison of Positron Annihilation with Other Defect-Sensitive Techniques.- A1 Semiconductor Data.- A2 Trapping Model Equations.- References.
479 citations
TL;DR: The physical properties of GaSb are briefly presented and the device implications reviewed in this paper, where a direct gap semiconductor (0.72 eV) capable of being doped either p or n type with good mobilities and it has significant electrooptical potential in the near IR range.
Abstract: The physical properties of GaSb are briefly presented and the device implications reviewed. GaSb is a direct gap semiconductor (0.72 eV) capable of being doped either p or n type with good mobilities and it has significant electro-optical potential in the near IR range. As a substrate, or active layer, GaSb can be employed in conjunction with many semiconductors such as (AlGa)Sb or In(AsSb) and has interesting heterojunction potential for detectors and lasers and quantum well structures.
184 citations
TL;DR: In this article, an intentionally doped gallium antimonide has been grown by molecular beam epitaxy on gallium arsenide and gallium anti-antimonide, and a strong correlation has been found between the quality of the layers and the degree of excess antimony flux; the best material was obtained with the minimum antimony stable growth at a particular substrate temperature.
Abstract: Unintentionally doped gallium antimonide has been grown by molecular‐beam epitaxy on gallium arsenide and gallium antimonide. Substrate temperatures in the range 480 to 620 °C and antimony to gallium flux ratios from 0.65 : 1 to 6.5 : 1 have been investigated. The deposition conditions have been related to growth morphology and to the electrical and optical properties of the epitaxial films. A strong correlation has been found between the quality of the layers and the degree of excess antimony flux; the best material in terms of both optical and electrical properties was obtained with the minimum antimony stable growth at a particular substrate temperature. All the material exhibited residual p‐type behavior. The lowest hole concentration achieved was 7.8×1015 cm−3 with a corresponding room‐temperature mobility of 950 cm2/V s. The narrowest PL (photoluminescence) features observed were peaks associated with bound exciton transitions with half‐widths of 2–3 meV.
145 citations