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Comprehensive study of photoinduced changes kinetics in ternary GeSb-Se chalcogenide thin films
Year: 2022
Type of publication: článek ve sborníku
Name of source: Proceedings of SPIE, volume 12151
Publisher name: SPIE - The International Society for Optical Engineering
Place: Bellingham
Page from-to: 121510F
Titles:
Language Name Abstract Keywords
cze Komplexní studie kinetiky světlem indukovaných změn v ternárních Ge-Sb-Se chalkogenidových vrstvách V této práci je studována kinetika fotoindukovaných změn v naprašovaných tenkých vrstvách ternárních Ge29Sb8Se63 chalkogenidů o různých tloušťkách. Pro panenské vrstvy byla pomocí spektrální elipsometrie stanovena optická šířka zakázaného pásu energií 1.87 +/- 0.02 eV a index lomu při 1550 nm 2.55 +/- 0.01. Teplotní žíhání způsobilo světlání vrstev s výsledným nárůstem optické šířky zakázaného pásu energií na 1.96 +/- 0.02 eV doprovázeno poklesem indexu lomu na 2.54 +/- 0.01. Následně byl pomocí analýzy transmisních dat z vláknového spektrometru sledován posun absorpční hrany. chalkogenidy; tenké vrstvy; světlem indukované změny; naprašování; fototmavnutí; fotosvětlání
eng Comprehensive study of photoinduced changes kinetics in ternary GeSb-Se chalcogenide thin films In this work, the kinetics of photoinduced changes in sputtered ternary Ge29Sb8Se63 chalcogenide thin films with different thicknesses is studied. The optical bandgap energy of virgin thin films is 1.87 +/- 0.02 eV and the refractive index at 1 550 nm is 2.55 +/- 0.01 as determined by spectroscopic ellipsometry using Cody-Lorentz oscillator model. An annealing treatment caused bleaching of thin films resulting in optical bandgap energy increase to 1.96 +/- 0.02 eV accompanied with refractive index decrease down to 2.54 +/- 0.01. Subsequently, the photoinduced shift of the absorption edge was determined by the analysis of transmission data obtained by fibre-coupled high-resolution spectrometer. The irradiation of virgin thin films by near-bandgap light coming from continuous-wave diode-pumped solid-state laser leads to a fast photodarkening (PD) followed by slow photobleaching (PB) effect. The PB effect persists in virgin films and the maximum magnitude of this effect was found in film with the thickness of similar to 350 nm. Rise of the optical bandgap energy was similar to 0.04 +/- 0.02 eV using optical intensity of 125.0 +/- 5.0 mW center dot cm(-2). On the other hand, in annealed thin films, only PD occurs under the same conditions indicating that the PB component of the photoinduced change disappears when the film is annealed. Maximum decrease in optical bandgap energy due to the PD effect in annealed films was about similar to 0.05 +/- 0.02 eV found in film with the thickness of similar to 650 nm. An influence of the thickness and laser optical intensity onto the kinetics of photoinduced changes is discussed. chalcogenides; thin films; photoinduced changes; sputtering; photodarkening; photobleaching