Molecular Beam Epitaxy of GaSb on GaAs Substrates with Compositionally Graded LT-GaAs_xSb_1-x Buffer Layers

We investigate the molecular beam epitaxy growth of GaSb films on GaAs substrates using compositionally graded GaAs_xSb_1-x buffer layers. Optimization of GaAs_xSb_1-x growth parameter is aimed at obtaining high GaSb crystal quality and smooth GaSb surface. The optimized growth temperature and thickness of GaAs_xSb_1-x layers are found to be 420^\circ\!C and 0.5 μm, respectively. The smallest full width at half maximum value and the root mean square surface roughness of 0.67 nm over 2\times2 μm^2 area are achieved as a 250 nm GaSb film is grown under optimized conditions.