Surface morphology and Raman scattering in GaAs/InAs(111) heterostructures grown by MOVPE

The surface morphology as a function of growth time in GaAs layers deposited by metal organic vapour phase epitaxy (MOVPE) on (111) oriented InAs substrates of A and B polarities has been investigated by atomic force microscope (AFM). In both cases a 3D growth of pyramidal islands has been found. The islands on the A surface coalesce at high growth times, whereas on the B surface the islands are larger and distributed with lower density. Raman measurements, through the red-shifts of the GaAs TO and LO phonons, give indication of the release of the tensile strain with increasing growth times and confirm the better uniformity of the growth on the A polar surface.