Effects of Be on the II-VI/GaAs interface and on CdSe quantum dot formation

The effects of Be on the II-VI/GaAs interface and on CdSe quantum dot (QD) formation were investigated. A (1 X 2) surface reconstruction was observed after a Be-Zn coirradiation of the (0 0 1) GaAs (2 X 4) surface. ZnBeSe epi layers grown after the Be-Zn coirradiation show very high crystalline quali ty with x-ray rocking curve linewidths down to 23 arcsec and a low etch pit density of 4 X 10(4) cm(-2), and good optical quality with a band-edge pho toluminescence (PL) emission peak linewidth of 2.5 meV at 13 K. However, Zn BeSe epilayers grown after Zn irradiation alone have poor crystalline quali ty and poor optical properties. Atomic force microscopy measurements show t hat CdSe QDs grown on ZnBeSe have higher density and smaller size than thos e grown on ZnSe. A narrower PL emission peak with higher emission energy wa s observed for the CdSe QDS sandwiched by ZnBeSe. These results indicate th at the formation of CdSe QDs as well as the II-VI/GaAs interface are modifi ed by the presence of Be. (C) 2001 American Vacuum Society.