SCANNING-TUNNELING-MICROSCOPY OF INAS GASB SUPERLATTICES WITH VARIOUSGROWTH-CONDITIONS/

Cross-sectional scanning tunneling microscopy (STM) is used to charact erize InAs/GaSb superlattices, grown by molecular beam epitaxy (MBE). Previous STM studies have found an interface asymmetry, with the inter faces of InAs grown on GaSb being rougher than those of GaSb on InAs. In the present work, a comparison is made between samples grown under various conditions, using elevated growth temperature o or using atomi c layer epitaxy (ALE). In both cases, the interface asymmetry is found to decrease compared to MBE growth at 380-degrees-C. In addition, Sb incorporation in the InAs layers is observed directly in the STM image s. It is argued that the additional roughness seen at the InAs on GaSb interfaces arises in part from incorporation of excess Sb into the gr owing InAs layers. Elevated temperatures reduces this incorporation, a nd hence produces smoother interfaces.