In situ x-ray topography measurements of the growth temperature dependenceof the critical thickness of epitaxial InGaAs on GaAs

In situ high-resolution double-axis x-ray topography measurements have been made of the critical thickness at which misfit dislocations form in strain ed layers of In(x)G(1-x)As grown epitaxially on (001) GaAs substrates. The critical thickness for formation of the initial fast B(g) misfit dislocatio ns was found to be close to, but larger than the predictions of the Matthew s-Blakeslee model. The discrepancy and the variation of the critical thickn ess with silicon doping have been modelled by inclusion of a Peierls stress in the force balance equation of misfit dislocation motion. Only a very sm all change was observed in the critical thickness as a function of growth t emperature. Inclusion of a temperature-dependent term in the Matthews-Blake slee model enabled an activation energy 0.3 +/- 0.2 eV to be determined.