Self-ordered InGaAs quantum dots grown at low growth rates

This study explores the effects of the growth rate on InGaAs/GaAs quantum dots (QDs) in producing ordered QD arrays. Surface morphological observations reveal that the dot density decreases as the growth rate increases and the QDs can be gradually self-ordered in the [1 (1) over bar0] direction. The threshold growth rate for one-dimensional self-ordered QD arrays is 0.054 mu m/h. This phenomenon is attributed to the preferential QD nucleation at the local strain maximum which is at the edge of the elongated step bunch. After the step bunches that elongated along [1 (1) over bar0] become the main feature on the wetting layer surface, the accumulated strain field on both step edges favors the nucleation of QDs. However, the concurrent decrease in QD size and the thinning of the wetting layer may be associated with the desorption of In and Ga adatoms and the lateral mass transport, respectively. (C) 2008 American Institute of Physics.