X-ray-absorption spectroscopy of ZnTe, CdTe, and HgTe: Experimental and theoretical study of near-edge structures

Abstract

X-ray near-edge absorption structure for ZnTe, CdTe, and HgTe has been studied with the use of synchrotron radiation. The $L_1$, $L_2$, and $L_3$ edges have been analyzed for Cd and Te in CdTe, as well as the $L_1$ and $L_3$ edges for Te in ZnTe and HgTe and the K edge of Zn in ZnTe. The experimental results are compared with absorption spectra which have been calculated on the basis of conduction-band state densities obtained from self-consistent linear muffin-tin-orbital calculations. A comparison of the experimental and theoretical results yields in most cases a good quantitative agreement, in particular for all $L_1$ and K edges analyzed. Due to deficiencies of the theoretical model, not quite so satisfactory results have been obtained for Cd $L_2$ and $L_3$ edges. In general, the results substantiate the opinion that the near-edge x-ray absorption for semiconductors can be satisfactorily described within the one-electron approximation, although for $L_2$ and $L_3$ edges the pre-edge region seems to be influenced by excitonic many-body effects, and that the combination of x-ray-absorption spectroscopy (XAS) and band-structure calculations constitutes a powerful tool for investigations of the empty states of these materials.