Glassy GaS: transparent and unusually rigid thin films for visible to mid-IR memory applications

Andrey Tverjanovich, Maxim Khomenko, Sergei Bereznev, Daniele Fontanari, Anton Sokolov, Takeshi Usuki, Koji Ohara, David Le Coq, Pascal Masselin, Eugene Bychkov

Результат исследований: Научные публикации в периодических изданияхстатьярецензирование

Аннотация

Phase-change materials based on tellurides are widely used for optical storage (DVD and Blu-ray disks), non-volatile random access memories and for development of neuromorphic computing. Narrow-gap tellurides are intrinsically limited in the telecom spectral window, where materials having a wider gap are needed. Here we show that gallium sulfide GaS thin films prepared by pulsed laser deposition reveal good transparency from the visible to the mid-IR spectral range with optical gap Eg = 2.34 eV, high refractive index nR = 2.50 over the 0.8 ≤ λ ≤ 2.5 μm range and, unlike canonical chalcogenide glasses, the absence of photo-structural transformations with a laser-induced peak power density damage threshold above 1.4 TW cm-2 at 780 nm. The origin of the excellent damage threshold under a high-power laser and UV light irradiation resides in the rigid tetrahedral structure of vitreous GaS studied by high-energy X-ray diffraction and Raman spectroscopy and supported by first-principles simulations. The average local coordination number appears to be 〈m〉 = 3.44, well above the optimal connectivity, 2.4 ≤ 〈m〉 ≤ 2.7, and the total volume of microscopic voids and cavities is 34.4%, that is, lower than for the vast majority of binary sulfide glasses. The glass-crystal phase transition in gallium sulfide thin films may be accompanied by a drastic change in the nonlinear optical properties, opening up a new dimension for memory applications in the visible to mid-IR spectral ranges.

Язык оригиналаанглийский
Страницы (с-по)25560-25573
Число страниц14
ЖурналPhysical Chemistry Chemical Physics
Том22
Номер выпуска44
DOI
СостояниеОпубликовано - 28 ноя 2020

Предметные области Scopus

  • Физика и астрономия (все)
  • Физическая и теоретическая химия

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