Preferred Orientation in Polycrystalline Cu(In,Ga)Se2 and Its Effect on Absorber Thin-Films and Devices

The purpose of this work is to investigate physical properties of Cu(In,Ga)Se2 polycrystalline thin-films exhibiting a high degree of preferred orientation. Specifically, by using Na-free Cu(In,Ga)Se2 thin-films, it is intended to experimentally determine differences (if any) between films with a (110/102)-preferred orientation and films with a (112)-preferred orientation. The approach to theproblem is a systematic comparative analysis of film and device properties in which the most significant variable is the preferred orientation of the Cu(In,Ga)Se2 polycrystalline absorbers. To complement the results of Na-free absorbers and devices, a micro-structural analysis is presented on (110)-oriented high efficiency Cu(In,Ga)Se2 absorbers (h>18%) that are grown on standard Mo-coatedsoda-lime glass substrates.