Effects of In Situ and Ex Situ Heat Treatment on Microstructural Features of Mo/CZTS Heterojunction Using X‐Ray Diffraction Technique

ABSTRACT A quaternary semiconductor Cu 2 ZnSnS 4 (CZTS) has appealing properties such as band gap and absorption coefficient. This broadens the application of CZTS in a variety of disciplines. However, CZTS has a number of challenges, including low crystallinity and phase purity. This effort attempts to optimize the in situ and post‐deposition annealing conditions in order to achieve higher crystallinity. CZTS thin films are deposited on DC sputtered molybdenum (Mo) thin layers on a glass substrate using RF sputtering. Two separate DC powers, 150 and 500 watts, were used to deposit Mo thin layers. Additional 100 and 200 watts RF power were used to deposit CZTS on top of Mo. The deposition temperature ranged from 100 °C to 300 °C, with 100 °C increments. The deposited CZTS layers were subjected to rapid heating and cooling utilizing the rapid thermal processing procedure. Microstructural characteristics were investigated utilizing a variety of approaches. The Scherrer method, Williamson–Hall method, size–strain method, Halder–Wagner method, and Wagner‐Aqua method were used to determine crystallite size and microstrain. Crystallite size is dependent on substrate crystallinity. Crystallinity increases at higher deposition temperatures. CZTS growth on Mo with 500‐watt DC power showed higher crystallinity than Mo with 150‐watt power. All methods used produce a comparable order of magnitude of crystallite size. Crystallite size increases with higher deposition temperatures. Post‐RTP treatment at 500 °C and 600 °C has a considerable effect on crystallite size.