Light-induced changes in the optical properties of thin films of Ge-S-Bi(Tl, In) chalcogenides

In this paper, we report some results from the study of changes in transmittance, reflectance and optical band gap of thin Ge-S-Bi(Tl, In) thin layers depending on the composition and the conditions of evaporation and illumination. Using two triple, TRfRm and TRbRm methods, the optical constants (n and k), and the thickness (d) of very thin layers from the Ge-S system have been determined to an accuracy of +/-2 nm. R-f, R-b and R-m is the reflection from the film side, from the glass substrate and that of 100 nm thick film deposited on Si substrate, respectively. The calculated values of the optical constants of the ternary chalcogenide films were compared with those obtained from the ellipsometric measurements and some conclusions for their practical applications were done. (C) 2003 Published by Elsevier B.V.