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On the high photodarkening values of some amorphous thin films of the Ge-As-S system

Authors: Kutálek Petr | Knotek Petr | Černošková Eva | Černošek Zdeněk | Samsonova Ekaterina | Tichý Ladislav

Year: 2024

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	On the high photodarkening values of some amorphous thin films of the Ge-As-S system	Amorphous chalcogenide glasses exhibit interesting properties such as a wide range of infrared transparency, high linear and nonlinear refractive index, low phonon energies and tunable properties by compositional tailoring. These unique properties make chalcogenide glasses and thin films good candidates for many applications such as sensors and detectors, lasers, optical fibers or waveguides. They also exhibit several photo-induced phenomena, such as photo induced expansion or photodarkening. In bulk glasses of the Ge As-S chalcogenide system, the magnitude of photodarkening reached as much as 5% of the band gap value for the specific chemical compositions. The reason for this maximal photodarkening remains unanswered. Amorphous thin films were prepared by the vacuum-thermal evaporation from the previously synthesized bulk glasses (Ge16As26S58, Ge20As25S55 and Ge30As30S40). Annealed thin films were illuminated with different light sources (band gap, over-band gap and sub-band gap photons) to induce the photodarkening. The nanophase separation of the thin films after the annealing and illumination was studied using the Raman microscopy and PeakForce Quantitative Nanoscale Mechanical mode of atomic force microscopy. Our main aim is to present some literature findings and our experimental results which suggest that the nanophase separation is likely to contribute significantly to the observed pronounced photodarkening within a limited region of a Ge-As-S chalcogenide system. It is characterized by a sulfur-poor chemical composition, with an arsenic content ranging approximately from 15 to 50 at%.	chalcogenides; Ge-As-S system; thin films; photodarkening; nanophase separation