Structural relaxation and optical properties in amorphous Ge33As12Se55 films

Amorphous Ge33As12S55 films prepared by ultra fast pulsed laser deposition (PLD) have been vacuum annealed over a range of different temperatures. Raman scattering measurements indicated that the features corresponding to Ge–Se and As–Se clusters increase in intensity with increasing annealing temperature (Ta) up to their respective glass transition temperature, and then decrease with further increasing Ta up to 300 °C. Optical property measurements showed that the refractive index deceases but the optical band gap increases with increasing Ta, and both of them could be fitted by the exponential function. The corresponding characteristic time extracted was found not to obey Arrhenius behavior, which is consistent with the existence of a broken network cut by cross-linking bonds and different clusters in films.