Structural analysis and chemical stability of Ge and As telluride glasses by Raman spectroscopy

Abstract

Telluride glasses such as Ge-As-Te, Ge-Te, and As-Te are of much interest due to their extensive infrared transparency. The structure of these glasses has also been broadly investigated, but Raman studies are rare and current literature data shows a significant level of disagreements and discrepancies. Here we show that the source of this disparity is two-fold, first the low damage threshold of these glasses requires low photon energy and low power to obtain reliable spectra, and second the unusual surface oxidation of telluride glasses leads to strong Raman artefact in relatively short time. Overall, high resolution spectra of freshly polished glasses obtained at low power with a near infrared source reveal that only four main modes are required to consistently interpret all Raman spectral features. Analysis of these Raman spectra confirm the presence of large chemical disorder in Ge-As-Te and As-Te glasses, consistent with previously reported spectroscopic studies.