Effect of substrate miscut on the electron mobility in InSb(001) structures on Ge and Ge-on-insulator substrates

Abstract

InSb epilayers and InSb/Al0.20In0.80Sb quantum wells were grown on Ge(001) substrates and Ge-on-insulator (GeOI)-on-Si(001) substrates by molecular beam epitaxy. Growth on both on-axis and 4°-off-axis substrate orientations was studied. Anti-phase domains were formed when InSb films were grown on on-axis substrates, but suppressed significantly by the use of 4°-off-axis substrates. Such off-axis substrates also reduced the densities of micro-twin defects and threading dislocations. The defect reduction resulted in an increase in the room-temperature electron mobility from 37,000 to 59,000 cm2/Vs in 4.0-μm-thick InSb epilayers and from 10,000 to 20,000 cm2/Vs in 25-nm-thick InSb quantum wells on Ge(001) and GeOI-on-Si(001) substrates.