An experimental study of the relaxation behaviour of strained Ga 1-xInxP layers grown on GaAs

The growth of strained Ga_1-xIn_xP alloys on GaAs substrate with the indium composition varying from 0 (GaP) to 1 (InP) was studied by means of reflection high energy electron diffraction (RHEED). Compressive layers (x>0.48) exhibit an InGaAs-like behaviour. Below 2% misfit strain (x⩽0.75) plastic relaxation occurs before the 2D-3D growth mode transition for which the lattice parameter relaxation is observed directly on the RHEED pattern. However, growth temperature has not a strong influence on the relaxation behaviour as in the InGaAs/InP system. On the other hand, if layers under tensile strain have a normal behaviour at low temperature, the critical thickness is found to be independent of the composition for x<0.35 at higher temperature (520°C). This unusual behaviour, as compared to strained InGaAs on InP layers for instance, could be associated to a spinodal decomposition of the GaInP alloy