Strain relaxation and defect reduction in InxGa1−xAs/GaAs by lateral oxidation of an underlying AlGaAs layer

Abstract

The strain relaxation in In0.25Ga0.75As and In0.4Ga0.6As grown on GaAs substrates at low temperature has been studied before and after laterally oxidizing an underlying Al0.98Ga0.02As layer. The relaxation as a function of layer thickness has been measured by cross-sectional transmission electron microscopy and x-ray analysis. It is found that oxidation of the Al0.98Ga0.02As layer improves the relaxation of the strained InxGa1−xAs layer. Moreover, the interfacial misfit dislocations have been removed, and the threading dislocation density has decreased approximately by one order of magnitude after oxidation.