In this work the influence of Cu on X-ray photoelectron Sr 3d and S 2p spec
tra for low Cu concentrations in SrS is studied. The Cu impurity in the SrS
lattice is detected by SIMS and X-ray diffractometry.
Careful analysis of the S 2p and Sr 36 spectra shows that the Cu impurity a
t concentrations less than the XPS sensitivity limit has its main influence
on the S 2p doublets that correspond to sulphur in SrS and to elementary s
ulphur clusters. SrS doping by Cu with subsequent annealing is accompanied
by a decrease in the sulphur clusters size and leads to downward band bendi
ng and/or n-doping of SrS. (C) 2000 Elsevier Science B.V. All rights reserv
ed.