Controlled cadmium telluride thin films for solar cells applications. First quarterly report, June 1, 1980-September 1, 1980

Abstract

During the first quarter of this renewed program, efforts have been extended mainly to set up a new ion beam sputtering system that would replace our existing r.f. sputtering system for the fabrication of doped CdTe thin films for solar cell applications. Preliminary attempts with this new equipment resulted in films with rather large grain size (0.8..mu.. - 1..mu..m) at an elevated substrate temperature. While this in itself is encouraging, certain difficulties were confronted in achieving the total control of the system which prevented the deposition of films with satisfactory quality. While attention is being given to bring the system under control, frequency dependent capacitance and conductance measurements were conducted on Schottky barrier diodes prepared from earlier deposited films. The results indicate presence of possible deep levels with distributed energy that might have limited the photovoltaic performance of these samples by reducing carrier lifetime. This appears to justify the decision to change the old r.f. sputtering system in favor of an ion beam sputtering system for this investigation.