Published online by Cambridge University Press: 28 February 2011
The optical properties and the thermal stability of Ge and Sn doped TeOx films prepared by coevaporating TeO2, Te, Ge and Sn are reported. These films are amorphous as-deposited and crystalline Te appears after annealing at, e.g., 100 to 250°C. As expected, the addition of Ge and Sn increases the absorption of the TeOx films at the wavelength of interest (e.g., 830 nm). However, the thermal stability of (TeO1.1)1-xGex (x=0 to ~0.7) films is found to decrease with increasing x initially, starting to increase with increasing x only after x reaches a value between 0.3 and 0.4. These results differ from those reported previously for Ge and Sn-doped TeOx films and from those observed for Te-Ge alloy films. Interpretations of these results based on a solid state reaction between TeO2 and Ge or Sn during deposition are presented and discussed.