REAL-TIME LASER-LIGHT SCATTERING STUDIES OF SURFACE-TOPOGRAPHY DEVELOPMENT DURING GAAS MBE GROWTH

In-situ laser light scattering is shown to yield valuable Teal-time information on the development of surface micro-topography during GaAs MBE growth. In-vacuo oxide desorption results in a large increase in scattered light intensity. Ex-situ atomic force microscopy has indicated the formation of a high density ( > 10(9) CM-2) of surface pits, attributed to localized GaAs consumption. Subsequent GaAs homoepitaxial growth (at 600-degrees-C) results in the development of an anisotropic ridged topography (ridge axes parallel to [110BAR]) with ridge dimensions increasing with epilayer thickness (peak-valley less-than-or-equal-to 12 nm for a 2.0 mum thick epilayer). Post growth in-vacuo annealing generates relatively flat surfaces, dominated by misorientation steps. For a 1 mum thick epilayer, annealing has a long time constant ( > 30 min at 600-degrees-C).