Role of Ge:As ratio in controlling the light-induced response of a-GexAs35-xSe65 thin films

Abstract

In this paper, we present interesting results on the quantification of photodarkening (PD), photobleaching (PB) and transient PD (TPD) in a- GexAs35-xSe65 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.

arXiv comment26 pages, 9 figures (including the supplementary section)

References in corpus (2)

• Fabrication and characterization of femtosecond laser written waveguides in chalcogenide glass
• Coexistence of fast photodarkening and slow photobleaching in Ge19As21Se60 thin films

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• First observation of temperature dependent lightinduced response of Ge25As10Se65 thin films
• Tailoring between network rigidity and nanosecond transient absorption in a-GexAs35-xSe65 thin films
• Ultrafast light-induced softening of chalcogenide thin films above the rigidity percolation transition