ORDERING IN GAINP ALLOYS ON GAAS - EFFECTS OF SUBSTRATE ORIENTATION

The effect of substrate orientation on (111) ordering in Ga(x)In(1-x)P alloys grown by Metal Organic Vapor Phase Epitaxy (MOVPE) is demonstrated. On (001) GaAs substrates, among the four possible variants only the {1/2 1/2 1/2} B are observed, and the misorientation towards the [11BAR0] direction makes the two B variants asymmetric to such a point that only one variant forms. On a (111)B GaAs substrate no ordering is observed. We propose a few simple rules controlling the growth process at the atomistic level which explain the absence of the A variants, the selection effect of the misorientation towards the [11BAR0] direction as well as the absence of ordering on (111)B substrates.