Fermi level unpinning of GaSb (100) using plasma enhanced atomic layer deposition of Al2O3
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Abstract
N-type and p-type GaSb metal-oxide-semiconductor capacitors (MOSCAPs) with atomic-layer-deposited (ALD) and plasma-enhanced-ALD (PEALD) Al2O3 dielectrics are studied to identify the optimum surface preparation and oxide deposition conditions for a high quality oxide-semiconductor interface. The ALD Al2O3/GaSb MOSCAPs exhibit strongly pinned C-V characteristics with high interface state density (D-it) whereas the PEALD Al2O3/GaSb MOSCAPs show unpinned C-V characteristics (low D-it). The reduction in Sb2O3 to metallic Sb is suppressed for the PEALD samples due to lower process temperature, identified by x-ray photoelectron spectroscopy analysis. Absence of elemental Sb is attributed to unpinning of Fermi level at the PEALD Al2O3/GaSb interface. (C) 2010 American Institute of Physics. [doi:10.1063/1.3492847]