Observations of roughening on In0.1Ga0.9As/GaAs surfaces at atomic force microscopy

Abstract

InGaAs layers of varying nominal epilayer thickness grown at different temperatures on GaAs substrates by molecular beam epitaxy are analysed by atomic force microscopy (AFM). This relatively new technique allows high-resolution imaging and analysis of surface morphology and roughness of semiconducting materials. The surface roughness and morphology of InGaAs grown at substrate temperatures ranging from 450 degrees C to 530 degrees C are analysed as the nominal epilayer thickness is increased from 100 AA to 800 AA. Over an area of 100 mu m2, an abrupt increase in the surface roughness indicates an acceleration of surface roughening mechanisms related to the process of strain relaxation. At higher nominal InGaAs thicknesses, surface corrugations were observed. The results indicate that thicker pseudomorphic InGaAs films on GaAs substrates can be grown at lower temperatures.