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.