Fermi Level Unpinning of GaSb (100) using Plasma Enhanced Atomic Layer Deposition of Al2O3

摘要

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 Dit whereas the PEALD Al2O3 /GaSb MOSCAPs show unpinned C-V characteristics low Dit. 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.