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 (T_a) up to their respective glass transition temperature, and then decrease with further increasing T_a up to 300 °C. Optical property measurements showed that the refractive index deceases but the optical band gap increases with increasing T_a, 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.