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Surface modification of bulk n-InAs (111)A etched in bromineemethanol
N. Eassa,R. Betz,E. Coetsee,H.C. Swart,A. Venter,J. R. Botha 한국물리학회 2013 Current Applied Physics Vol.13 No.2
X-ray photoelectron spectroscopy, field emission scanning electron microscopy, Raman and photoluminescence spectroscopy were used to evaluate the surface properties of n-type InAs (111)A etched in a 1% Bremethanol solution. Etching completely removes the native oxides from the surface and enhances the photoluminescence response. The adsorption of bromine onto the InAs surface leads to the formation of IneBrx and AseBrx bonds (x ¼ 1, 2, 3) as inferred from changes in the In 3d3/2;5/2 and As 3d core level binding energies. The etch rate is found to decrease due to strong anisotropic effects and the high volatility of the bromine species. A 1 min Bremethanol etch was found to enhance the photoluminescence intensity by a factor of 3, probably due to a reduction in the surface state density upon deoxidation of the surface. This is thought to be due to reductions in the surface state density. The presence of native oxides enhances both the surface accumulation layer and the surface state density.
The Optical and Electrical Properties of AP-MOVPE GaSb Grown Using TEGa and TMSb
S. S. Miya,V. Wagener,J. R. Botha 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2
High quality undoped metal-organic vapour phase epitaxial (MOVPE) GaSb layers have been grown on GaAs using the trimethylantimony/triethylgallium (TMSb/TEGa) precursor combination at 550°C and atmospheric pressure. The effects of the TMSb to TEGa flux ratio (i.e. V/III ratio) on the surface morphology and optical and transport properties of these layers have been investigated. The transport properties were found to be comparable to the best reported for un-doped GaSb grown using the same precursors at low reactor pressures. Two models (using either two monovalent acceptors or one divalent acceptor) were used to estimate the density of native acceptors and the ionization energy of the acceptors in GaSb. These models showed the shallow acceptor activation energy or first ionization energy to be ~30 meV (falling within the reported range of 20 - 40 meV). The ionization energy of the deeper acceptor or second ionization of the level was determined to be ~120 meV.