Effects of In composition on the surface morphology of self-assembled In _x Ga_1−x Sb/GaAs quantum dots

Abstract

We investigate the influence of the In composition x on the surface morphology of In x Ga1−x Sb quantum dots (QDs) grown by molecular beam epitaxy. In x Ga1−x Sb QDs are successfully formed at x ≤ 0.5 on GaAs(100) and x ≤ 0.6 on GaAs(311)A, where the QD size is larger and their density is lower on GaAs(100) than those on GaAs(311)A at any x. The shape and density n QD of In x Ga1−x Sb QDs on GaAs(100) is more significantly affected by x than those on GaAs(311)A; the aspect height-to-radius ratio h/r increases about twofold on GaAs(100) with increasing x, but the increase of h/r is only 1.1 times on GaAs(311)A. As x increases from 0.0 to 0.5, n QD decreases by a factor of 150 on GaAs(100), while the decrease of n QD is only 7 times on GaAs(311)A. The comparison between the experiment and a rate equation model suggests that the hopping barrier energy between surface sites depends linearly on x.