Structural Perfection of Selective GaAs Regions in Si Substrate Windows

Abstract

Structural perfection are studied of GaAs selective regions as grown in Si substrate windows on (100) and (111) GaAs nucleation wafers. The dislocation density distributions across the thickness and over the surface of 300 × 300 μm2 epitaxially grown selective regions are determined. The dislocation density on the selective (100) wafer-grown region surfaces is shown to be some 1.5 to 2 orders of magnitude lower than that of the nucleation wafer, and an order of magnitude lower as compared with continuous epitaxial layers. An expression is given which describes the proposed model of dislocation density reduction across the thickness of epitaxial selective regions. It is found that the maximum density is observed at the centre of the selective region. Away from the centre, the density reduces and at a distance of some tens of microns, i.e. at the selective region edge, there are practically no dislocations. [Russian Text Ignored].