Band alignment at sputtered ZnSxO1 x Cu In,Ga Se,S 2 heterojunctions

Abstract

Valence band offsets amp; 916;EVBM at ZnSxO1 x Cu In,Ga Se,S 2 CIGSSe heterojunctions have been studied by photoemission spectroscopy XPS, UPS as a function of composition x in sputtered ZnSxO1 x films. In the composition range from ZnO to ZnS we found amp; 916;EVBM between 2.1 0.3 eV and 0.8 0.4 eV, respectively. Considering the optical band gaps, the conduction band offsets amp; 916;ECBM range from 0.1 0.3 eV to 1.4 0.4 eV. These results suggest that sputtered ZnSxO1 x is suitable as substitution for the CdS buffer and ZnO window layers in standard chalcopyrite based solar cells. Current voltage characteristics of the solar cells have been investigated as a function of the composition