Self-assembled InAs quantum dots on anti-phase domains of GaAs on Ge substrates

The authors report the formation of self-assembled InAs quantum dots (QDs) grown on GaAs/Ge substrates having anti-phase domains (APDs) by molecular beam epitaxy. The AFM images of InAs QDs grown on different GaAs thicknesses are shown and compared. The samples with InAs coverage of 1.80 MLs with GaAs thickness of 300 and 700 nm show non-uniformed size distribution of the dots. Due to anisotropic property of quantum dots, ellipsoidal quantum dots appear. Unexpectedly, most of InAs quantum dots align perpendicularly to anti-phase boundary (APB) and to quantum dot alignment formed in adjacent domains. Photoluminescence spectrum excited by 20 mW 476-nm Ar+ laser at 20 K does not show emission peak of InAs QDs. This is due to defects in the GaAs buffer layer.