Improving the surface morphology of InSb quantum-well structures on GaAs substrates

The electron mobility in AlxIn1-xSb/InSb quantum-well structures grown on G aAs substrates is reduced due to the presence of crystalline defects. In st ructures grown by molecular beam epitaxy, we observe three kinds of defects : hillocks, oriented abrupt steps, and square mounds. The hillocks and orie nted abrupt steps are caused by lattice mismatch. The square mounds arise o nly when AlxIn1-xSb is grown and probably originate near the AlxIn1-xSb/buf fer layer interface. The optimum V/III growth rate ratio fur reducing the s quare-mound density is approximate to 1.1 at a substrate temperature of sim ilar to 440 degrees C. (C) 2000 American Vacuum Society.