LOW-TEMPERATURE GROWTH AND CHARACTERIZATION OF GAAS EPITAXIAL LAYER ON (111)B GAAS SUBSTRATES

Unique properties of homoepitaxial (111) GaAs layers grown at low temp eratures have not been realized mainly due to very narrow temperature range for the layer-by-layer growth. In this study, molecular-beam epi taxy growth of GaAs (111) layers on a tilted (111)B substrate at 350-d egrees-C is reported. Reflective high-energy electron diffraction obse rvation during the low-temperature growth shows an initial surface str ucture of (2 x 2) which changes to (1 x 1) at the beginning of the gro wth. Diffraction spots appear at the growth layer thickness of 75 nm. These extra spots are attributed to twins and stacking faults confirme d by transmission electron microscopy. GaAs (111) layers grown at 350- degrees-C have a high density of twins and a specular surface. High-te mperature growth of (111) GaAs on a low-temperature buffer layer leads to a tenfold increase in the surface roughness.