Combined Raman-DLTS investigations of n-type Cu–In–S absorber layers grown on Cu tape substrate (CISCuT)

Thin absorber films grown by the CuInS2-on-Cu-tape (CISCuT) method were studied by Raman spectroscopy and deep-level transient spectroscopy (DLTS). Raman measurements revealed a degradation of crystalline quality and a growth of the CuAu fraction with the increase of Cu-tape velocity through the sulfur chamber, whereas DLTS method – corresponding variations in the magnitude of the dominating peak E1. The origin of the E1 peak was established from the correlation of Raman and DLTS results and ascribed to defect states at the interface between chalcopyrite and CuAu phase.