Self-assembled InAs quantum dots (QDs) on graded Si1-xGe x /Si substrate were observed to adopt a truncated pyramidal shape when capped with GaAs. Our results suggest that atomic migration from the QD apex to the GaAs cap layer contributes to the formation of the symmetrical V-shaped defects near the top edges of the truncated pyramidal QDs. By employing an In0.1Ga0.9 As cap, material migration and strain around the QDs were reduced, hence suppressing the occurrence of the V-shaped defects. Furthermore, photoluminescence thermal quenching rate of the QDs is significantly slower compared to the QDs with GaAs cap. Finally, 1.3μm room-temperature photoluminescence was observed.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)