Correlation of the near-infrared optical absorption with Cu concentration in coevaporated Cu-In-S films

The films, characterized by spectrophotometry (A%) and sheet resistance (R) by four-terminal sensing measurement, were classified in compositional groups by the use of the two-dimensional parameter (R, A%). Interestingly, the optical absorption A% was linearly correlated with Cu content in our compositional range while R presents a jump back related with the variation of S concentration. The independence of R and A% in this case is discussed in terms of different conduction mechanisms.