Control of Dislocations in GaAs Grown on Si(211) by Molecular Beam Epitaxy

摘要

The dislocation arrangements in gallium arsenide films grown on silicon substrates with (211) surface orientations were directly determined using transmissions-electron microscopy in planar and cross-sectional views. The dislocations consisted of high density networks at the GaAs-Si interface and arrays of linear dislocations that propagated from the interface to the surfacer of the film on the (111) planes. Burger's vector determination of the arrays indicated that dislocations are introduced into the film primarily by a glide and that the linear arrays are a remnant of the interface network. When strained layer InxGas(1-x)As/GaAs superlattices were used, the linear arrays were observed to form a closed dislocation network, with the top of the loop structure coincident with the top of the superlattice. The dislocation density was markedly reduced above the superlattice. Our results indicate that careful control of the strain can be an effective means of altering dislocation distributions in the films. Keywords: Molecular beam epitaxy. (Reprints)