Growth of InSb and InAs_1-xSb_x on GaAs by molecular beam epitaxy

InSb and InAs_1-xSb_x epitaxial layers have been successfully grown on (100)GaAs substrates by molecular beam epitaxy. Remarkably good morphologies were obtained despite the large lattice mismatch (14%) between InSb and GaAs. Room-temperature electron mobilities as high as 57 000 cm²/V s were measured in InSb layers of about 5 μm thick with N_D-N_A∼1.6×10¹⁶ cm^-3. The substrate temperature and Sb/In flux ratio were found to critically influence the quality of InSb epilayers. By employing dimeric instead of tetrameric sources, the composition of the InAs_1-xSb_x films was observed to be relatively independent of substrate temperature. Electron mobilities of 20 000 and 8800 cm²/V s, at 300 and 77 K, respectively, were obtained for a 1.6-μm-thick InAs_1-xSb_x (x=0.67) layer.