Internal strain analysis of CdTe thin films deposited by pulsed DC magnetron sputtering

Thin film CdTe was deposited by pulsed dc magnetron sputtering. Magnetron sputtering offers significant advantages for the deposition of thin film photovoltaic including low deposition temperatures and excellent coating uniformity. However the films are susceptible to stress due to the relatively high deposition energy. In this study, deposition temperature and argon gas flows have been used to minimize stress in the deposited films. TEM imaging was used to investigate the crystalline structure of the deposited films and XRD was used to measure strain. XRD analysis showed that stress can be minimized by depositing the CdTe thin film at temperatures of approximately 200°C using relatively high argon gas flows of 60 sccm. Moreover, this increase in substrate temperature has the further advantage of promoting larger grain sizes up to 500nm in the deposited films.