Quantitative topographic assessment of Cu incorporation in GaAs

The modification of the bulk resistivity of semi-insulating GaAs caused by incorporation of copper has been studied. Wafers cut from an ingot annealed , intentionally Cu contaminated LEC grown crystal were investigated optical ly and electrically. A characteristic variation pattern of the Cu related p hotoluminescence intensity, gradually decreasing towards the center, is obs erved. The resistivity exhibits a quite similar radial dependence. The resu lts convincingly show that Cu is diffusing across macroscopic distances int o GaAs and is responsible for the radial resistivity variation. The topogra phic correlation allows to quantify the Cu acceptor content. (C) 2000 Elsev ier Science B.V. All rights reserved.