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Journal ArticleDOI

Gallium vacancy and the residual acceptor in undoped GaSb studied by positron lifetime spectroscopy and photoluminescence

20 May 2002-Applied Physics Letters (American Institute of Physics)-Vol. 80, Iss: 21, pp 3934-3936

AbstractPositron 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.

Topics: Positron Lifetime Spectroscopy (62%), Vacancy defect (55%), Acceptor (54%), Gallium antimonide (51%), Gallium (51%) more

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Abstract: Acceptors in liquid encapsulated Czochralski-grown undoped gallium antimonide (GaSb) were studied by temperature dependent Hall measurement and positron lifetime spectroscopy (PLS). Because of its high concentration and low ionization energy, a level at EV+34meV is found to be the important acceptor responsible for the p-type conduction of the samples. Two different kinds of VGa-related defects (lifetimes of 280ps and 315ps, respectively) having different microstructures were characterized by PLS. By comparing their annealing behaviors and charge state occupancies, the EV+34meV level could not be related to the two VGa-related defects.

33 citations

Journal ArticleDOI
Abstract: Undoped Ga-Sb samples were investigated by positron lifetime spectroscopy (PAS) and the coincident Doppler broadening (CDB) technique. PAS measurement indicated that there were monovacancy-type defects in undoped Ga-Sb samples, which were identified to be predominantly Ca vacancy (V-Ga) related defects by combining the CDB measurements. After annealing of these samples at 520 C, positron shallow trapping have been observed and should be due to Ga-Sb defects. Undoped Ga-Sb is intrinsically p-type having a residual carrier density of 10(16)-10(17) cm(-3). And the Ga-Sb antisite defects are stable in the (0), (1-) and (2-) charge states and act as a double acceptor. Thus, we infer that Ga-Sb antisite defects are the acceptor contributing to the p-type conduction for undoped samples. (C) 2004 Elsevier B.V All rights reserved.

27 citations

Journal ArticleDOI
Abstract: A green long persistent luminescence (LPL) phosphor Ca3Ga4O9:Tb3+/Zn2+ was prepared. Ca3Ga4O9 matrix exhibits blue self-activated LPL due to the creation of intrinsic traps. When Tb3+ is doped, the photoluminescence (PL) and LPL colors change from blue to green with their intensities significantly enhanced. The doping of Zn2+ evidently improves the PL and LPL performances of the Ca3Ga4O9 matrix and Ca3Ga4O9:Tb3+. The thermoluminescence (TL) spectra show that a successive trap distribution is formed by multiple intrinsic traps with different depths in the Ca3Ga4O9 matrix, and the incorporation of Tb3+ and Zn2+ effectively increases the densities of these intrinsic traps. The existence of a successive trap distribution makes the Ca3Ga4O9:Tb3+/Zn2+ phosphor exhibit thermally stable PL and LPL. It is indicated that this phosphor shows great promise for the application such as high-temperature LPL phosphor.

16 citations

Journal ArticleDOI
Abstract: Different diffusion sources were used to study Zn diffusion in n-GaSb. We found that the Ga atoms from the diffusion sources suppressed the formation of the high-concentration surface diffusion fronts in Zn profiles, thus converting the kink-and-tail-shaped profile to the box-shaped profile. Our analysis demonstrated that both the surface and the tail regions in the kink-and-tail profiles showed high-quality regularities. The analysis also revealed that the formation mechanism of the box profiles is the same as that of the tail region of the kink-and-tail profiles. The similarities of the photoluminescence signals between the main region of the box profiles and the tail region of the kink-and-tail profiles substantiated our findings.

15 citations

Journal ArticleDOI
Abstract: The recent results for the self-diffusivities, D(Ga) and D(Sb), of Ga and Sb in GaSb obtained by Bracht et al (Bracht H, Nicols S P, Walukjewicz W, Silveira J P, Briones F and Haller E E 2000 Nature 408 69 and Bracht H, Nicols S P, Haller E E, Silveira J P and Briones F 2001 J. Appl. Phys. 89 5393) are compared and related to the earlier measurements by Weiler and Mehrer (Weiler D and Mehrer H 1984 Phil. Mag. A 49 309). It is proposed that the differences between the two sets of data are due to higher concentrations of hydrogen impurity in the samples of Weiler and Mehrer. The experimental evidence indicates that the diffusion mechanisms associated with D(Ga) and D(Sb) both have two parallel mechanisms. For D(Ga) the native defects involved are the Frenkel pair, GaiVGa, and the Ga vacancy, VGa. For D(Sb) one mechanism is due to the defect pair SbiVGa and the second to either the vacancy pair VGaVSb or the triple defect VGaGaSbVGa. It is proposed that the mobilities of all these defects, excepting GaiVGa, are enhanced in the presence of hydrogen as an impurity in the GaSb lattice. On this basis the differences in the data obtained by Bracht et al and Weiler and Mehrer can be reconciled. It is also shown that measured free hole concentrations identify Ga2−Sb as the residual acceptor in GaSb and that undoped GaSb is intrinsic at diffusion anneal temperatures.

13 citations

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Journal ArticleDOI
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

624 citations

01 Jan 2003
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.

461 citations

Journal ArticleDOI
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.

179 citations

Journal ArticleDOI
Abstract: A study was made of the influence of direction of growth, melt composition and growth speed upon the relative occurrence of the residual acceptor centres in melt-grown GaSb single crystals Special attention was given to effects arising from the fact that the solid-liquid interface can be more or less faceted during growth Crystal growth in the [111] direction was found to be different from growth in the [111] direction In the discussion the possibility of a simple defect centre is ruled out and it is shown that of the more complex centres the GaSbVGaa centre fits the present data best

142 citations