Structural and optical characterization of amorphous As40S60 and As40Se60 films prepared by plasma-enhanced chemical vapor deposition

Amorphous chalcogenide films of chemical compositions As40S60 and As40Se60 have been prepared by plasma-enhanced chemical vapor deposition. An improved optical characterization method suitable for non-uniform thin films, which also takes into consideration the weak absorption in the substrate, has successfully been applied. The values of the average thickness and thickness variation, d ¯ and Δd, respectively, were crossed-checked with those measured by use of a surface-profiling stylus instrument, and differences between the directly measured and the optically calculated values were, in all cases, less than 2%. A comparison between the structural and optical properties of these PECVD films, and those of the same chemical composition prepared by thermal evaporation, is systematically made in this paper.