TEMPERATURE EFFECT ON SURFACE FLATNESS OF MOLECULAR-BEAM EPITAXY HOMOEPITAXIAL LAYERS GROWN ON NOMINAL AND VICINAL (111)B GAAS SUBSTRATES

For the first time a comparison is made between the surface characteri stics of layers simultaneously grown on nominal and on vicinal (111)B substrates under the 1x1 reconstruction regime which provides flat sur faces for both orientations. The influence of growth temperatures, 600 and 700 degrees C, on surface characteristics is thoroughly reviewed based on an atomic force microscopy study. This study yields additiona l insight into results already reported on growth mechanisms occurring along these two orientations for the root 19x root 19 growth regime. For the nominal (111)B layers, it will be shown that monoatomic steps at the surfaces define large atomically flat plateaus at both temperat ures. At 600 degrees C, growth will be shown to proceed mainly through the development of two-dimensional nuclei, which are limited in size to a critical value and can coalesce by a proximity effect. These nucl ei will be shown to be much smaller at 700 degrees C, thereby turning the step flow into the main mechanism occurring at that temperature. F or the vicinal orientation, monoatomic-stepped and step-bunched surfac es grown at 600 and 700 degrees C, respectively, will be obtained unde r our 1x1 growth conditions, the same as in the root 19x root 19 regim e. (C) 1998 American Vacuum Society.