OBSERVATIONS OF ROUGHENING ON IN0.1GA0.9AS/GAAS SURFACES BY ATOMIC FORCE MICROSCOPY

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 angstrom to 800 angstrom. Over an area of 100 mum2, 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.