Observations of the Solid Phase Epitaxial Regrowth for GaAs/Si

ABSTRACTThe changes in defect structure caused by an anneal are studied by TEM for thin GaAs layers on Si. A low growth temperature of 450°C is always used for the first 300Å. When it is first deposited this layer contains considerable disorder which consists of planar defects, {112} epitaxy and an irregular distribution of dislocations. Annealing of the layer gives rise to a solid phase regrowth that consumes the misoriented and much of the twinned crystal and produces regular misfit dislocation arrays. Continued growth at high temperature can reduce the twin densities to below the detection limit of TEM. It is this solid phase transformation of this layer that allows good epitaxy to continue.