Amorphous thin films for solar cell application. Quarterly report No. 3, October 1, 1979-December 31, 1979

The identification, content, and role of impurities in a-Si thin films are sources of speculation not only for possible device performance degradation but also for their impact on film-property diagnosis. This concern is presently shared by those using all deposition processes, with oxygen and argon receiving attention as the most commonly introduced impurities. Oxygen to some degree (and with nitrogen) might have beneficial effects on film photoconductivity; yet device performance is said to suffer when oxygen concentration approaches one percent. Argon inclusion effects on film structure, resulting post-deposition oxidation, and the nature of the defect state are indicated but unclear. Emphasis this quarter was on (1) the measurement of oxygen concentration profiles through the film using Rutherford backscattering and nuclear reaction methods; and (2) the control over oxygen inclusion in the sputtered films. Progress is reported in detail.