Characterization of ZnO/CdS/CuInSe 2 Thin-Film Solar Cells by Deep-Level Transient Spectroscopy

Abstract
Trap energy levels in CuInSe2 (CIS) films have been measured by means of deep-level transient spectroscopy (DLTS). ZnO/CdS/CIS solar cells with conversion efficiencies of 5–11% were used as samples. Hole traps were detected for all samples measured in this study. Activation energy of traps in each sample was estimated to be in the range from 78 to 226 meV, which is shallower than any other reported values. Characteristics of the trap were thought to depend on the fabrication process of CIS films.