EFFECT OF DEPOSITION PRESSURE ON THE OPTICAL AND STRUCTURAL PROPERTIES OF NANO GTC FILMS.

XRD of thermally evaporatedGe0.15Te0.80Cu0.05thin films at higher deposition pressure show amorphous state while the lower deposited films show poly crystalline state. Different preferred orientations were identified; (222), (411) for GeTe4, (101), (003) for Te and (311) for GeTe. The corresponding crystallites sizes are 5,10,11,10 and 9 nm respectively. The lower deposition pressure, LDP develops the optical properties; direct, indirect optical gap and phonon energy are increasing as a function of deposition pressure. Optical gap was affected by carrier concentration. Burstein-Moss effect, B-M effect was used to discuss the variation of the optical properties. [ABSTRACT FROM AUTHOR]