InSb-based epilayers and quantum wells grown on off-axis and on-axis Ge(001) substrates by MBE

The highest electron and hole mobilities in quantum wells (QWs) at room temperature have been observed in QWs made of InSb and Ge, respectively. This provides a motivation for integrating InSb and Ge devices onto a single wafer. We report our investigation of the molecular beam epitaxy (MBE) of InSb epilayers and InSb/Al$_{x}$In$_{1-x}$Sb QWs on Ge(001) substrates that are on-axis or 6$^{o}$-off-axis. The formation of anti-phase domains (APDs) makes growth of high-quality InSb films on Ge a substantial challenge. Reflection high-energy electron diffraction patterns during growth indicate a two-domain and single-domain reconstruction for epilayers grown on on-axis and off-axis substrates, respectively. The narrowest X-ray rocking curve width is 215 arc sec for a 2.0-$\mu $m-thick InSb epilayer on an off-axis substrate. The room temperature electron mobility of a 4.0-$\mu $m-thick InSb epilayer was 1.5 times higher for growth on an off-axis Ge(001) substrate (53,500 cm$^{2}$/V-s) compared to growth on an on-axis substrate (34,500 cm$^{2}$/V-s). These data indicated that APDs are suppressed in the structures grown on off-axis Ge(001) substrates.