Role of strain and growth conditions on the growth front profile of InxGa1−xAs on GaAs during the pseudomorphic growth regime

Abstract

Theoretical and experimental studies are presented to understand the initial stages of growth of InGaAs on GaAs. Thermodynamic considerations show that, as strain increases, the free‐energy minimum surface of the epilayer is not atomically flat, but three‐dimensional in form. Since by altering growth conditions the strained epilayer can be grown near equilibrium or far from equilibrium, the effect of strain on growth modes can be studied. In situ reflection high‐energy electron diffraction studies are carried out to study the growth modes and surface lattice spacing before the onset of dislocations. The surface lattice constant does not change abruptly from that of the substrate to that of the epilayer at the critical thickness, but changes monotonically. These observations are consistent with the simple thermodynamic considerations presented.