Univerzita PardubiceFakulta chemicko- technologická

Univerzita Pardubice

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Photodarkening in some amorphous Ge-As-S thin films and possible influence of nanophase separation

Autoři: Kutálek Petr | Knotek Petr | Černošková Eva | Samsonova Ekaterina | Tichý Ladislav

Rok: 2024

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
eng	Photodarkening in some amorphous Ge-As-S thin films and possible influence of nanophase separation	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 [1]. These unique properties make chalcogenide glasses and thin films good candidates for many applications such as sensors and detectors, lasers, optical fibers, waveguides and phase-change memories. They also exhibit several photo induced phenomena, such as photo-induced expansion and also photodarkening. In bulk glasses of the Ge As-S chalcogenide system, the magnitude of photodarkening reached even 5% of the band gap value [2] for the specific chemical compositions. The reason for the maximal photodarkening for these specific compositions remains unanswered. Amorphous thin films with the chemical compositions Ge12As33S55, Ge18As30S52 and Ge27As29S44 and an average thickness of ≈ 910 nm were prepared by the vacuum thermal evaporation from the previously synthesized bulk glasses. Annealed thin films were illuminated with the different light sources (band gap, over band gap and sub band gap photons were used) to induce the photodarkening. The nanophase separation of thin films after the annealing and illumination was studied using the Raman microscopy. The PeakForce Quantitative Nanoscale Mechanical mode of atomic force microscopy was used as an alternative method to determine the possible presence of nanophase separation in the studied Ge-As-S thin films. Our main aim is to present some literature findings and our experimental results which suggest that the nanophase separation likely contributes 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 20 to 40 at.%.	chalcogenides; Ge-As-S system; thin films; photodarkening; nanophase separation