title: Role of Ge:As ratio in controlling the light-induced response of a-Ge(x)As(35-x)Se65 thin films.
abstract: In this paper, we present interesting results on the quantification of photodarkening (PD), photobleaching (PB) and transient PD (TPD) in a-Ge(x)As(35-x)Se65 thin films as a function of network rigidity. Composition dependent light-induced responses of these samples indicate that there exist two parallel competing mechanisms of instantaneous PD arising from the As part of the network, and PB arising from the Ge part of the network. Raman spectra of the as-prepared and illuminated samples provide first direct evidence of the light-induced structural changes: an increase in AsSe3/2 pyramidal and GeSe4/2 corner-sharing tetrahedra units together with new Ge-O bond formation and decrease in energetically unstable edge sharing GeSe4/2 tetrahedra. Importantly, for a fixed Se concentration, Ge:As ratio plays the critical role in controlling the net light-induced response rather than the much believed rigidity of the glassy network.
authors: Department of Physics, Indian Institute of Science Education and Research, Bhopal 462023, India.
authors: Pritam
authors: P
authors: Khan
authors: Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
authors: H
authors: H
authors: Jain
authors: Department of Physics, Indian Institute of Science Education and Research, Bhopal 462023, India.
authors: K V
authors: KV
authors: Adarsh