Quantitative local environment characterization in amorphous oxides

We perform density-functional-theory calculations of electronic core levels to obtain the tellurium x-ray photoelectron spectra in the amorphous solar-energy materials CdTeO_x (x=0.2, 1, 2, and 3). We quantify the distribution of local tellurium environments that sum up to the total two-peak structure in the experimental spectrum. The general trend is that the more oxygen neighbors tellurium has the bigger the shift of its core-level energy. However, due to the structural complexity, the relation between the core-level shift and the number of oxygen neighbors does not obey simple rules. Hence, we show the importance of computer simulations when interpreting x-ray photoelectron spectra in this system, in particular, and amorphous oxides in general.