Fabrication of Buffer-Window Layer System for Cu(In, Ga)Se2 Thin Film Devices by Chemical Bath Deposition and Sol–Gel Methods

Abstract

Recently, nontoxic fabrication for Cu(In, Ga)Se2 thin films gained increasing popularity. In this work, chemical bath deposition and Sol–gel methods were utilized in the fabrication of an environmentally buffer-window (ZnS-ZnO/ZnO:Al) layer system for Cu(In, Ga)Se2 thin film devices. The influences of conditions like annealing temperature, coating times, and Al-doping amount were investigated. The surface morphology and optical properties illustrated a compact and uniform ZnS film with a band-gap of 3.78, which can be a good alternative to CdS film. Resistivity of 0.35 Ω·cm for the ZnO/ZnO:Al film was achieved by the ideal condition of 9 coating times and 5 Al-doping amounts. A cross-sectional view of the complete Cu(In, Ga)Se2 thin film was obtained, and the structure status was analyzed.