Influence of nucleation procedures on stress relaxation in heterostructures: GaAs/Si (100)

Abstract

Stress relaxation behavior at the start of molecular beam epitaxial growth of GaAs layers on Si (100) 2°off substrates was studied as a function of nucleation procedures. Two alternative methods were investigated: (i) the standard two-step technique in which growth is initiated at moderate temperature and growth rate, and (ii) a procedure in which a succession of amorphous thin GaAs layers are deposited and thermally crystallized at each step. The results obtained by in situ reflection high-energy electron diffraction analyses evidence a strong dependence of stress relaxation on the nucleation procedure used: in the first case, stress relaxation occurs abruptly at the start of nucleation although, in the second case, relaxation occurs progressively. These results are discussed in terms of the modes of growth involved.