Reduction of Rocksalt Phase in Ag -Doped Ge2Sb2Te5 : A Potential Material for Reversible Near-Infrared Window

Abstract

Phase-change materials are attracting much attention in the scientific and engineering communities owing to their applications and underlying basic phenomena. Ge 2 Sb 2 Te 5 is reversible-phase-change material (amorphous to crystalline and vice versa) that is used for optical data storage and phase-change random-access memory and has recently been explored for use as a reversible near-infrared (NIR) window [Singh et al., Appl. Phys. Lett. 111, 261102 (2017)]. For a reversible NIR window, large transmission contrast between two phases and low phase-transition temperature are required to reduce the power consumption. In the present work, phase transition in thermally deposited (Ge 2 Sb 2 Te 5) 100−x Ag x (x = 0, 1, 3, 5, and 10) thin films is achieved by vacuum thermal annealing. Transmission sharply decreases with phase transition in the NIR region. Ge 2 Sb 2 Te 5 shows large transmission contrast (more than 50%) in the wavelength range from 1600 to 3200 nm with phase transition from an amorphous to a hexagonal-closepacked structure at 260 • C. In (Ge 2 Sb 2 Te 5) 90 Ag 10 thin films, a similar transmission contrast is achieved at a comparatively lower temperature (160 • C) due to reduction of the rocksalt phase. Distortion of the host lattice with addition of 10% Ag is confirmed from the drastic change in the density of states in the valence band and the shift in core-level (3d) spectra of Ag, Sb, and Te. This distortion enables a hexagonal-closepacked phase in (Ge 2 Sb 2 Te 5) 90 Ag 10 thin films to be obtained at 160 • C. (Ge 2 Sb 2 Te 5) 90 Ag 10 could be a potential candidate for a reversible NIR window as it requires less power to achieve phase transition and high transmission contrast.

Temperature-Dependent Ultrafast Charge Carrier Dynamics in Amorphous and Crystalline Sb2Se3 Thin Films

“…In the present study, the bulk alloy of Sb 2 Se 3 was prepared by the melt quenching technique from highly pure (99.999%, trace metal basis) antimony and selenium. , Thin films of newly synthesized Sb 2 Se 3 alloy were deposited on glass substrates using the thermal evaporation (HHV-BC-300) technique. , The thickness of films was measured in situ by a digital thickness monitor (HHV DTM-101). As-deposited film was annealed at 250 °C in vacuum (10 –3 mbar) for 2 h. The structure of as-deposited and annealed thin films was investigated by the X-ray diffraction (XRD) technique using an X-ray diffractometer (Bruker D8 Advance) with radiation of Cu Kα 1 (λ = 1.5406 Å) in the 2θ range of 10–80°.…”

Thickness dependent structural, morphological and optical properties of molybdenum oxide thin films

“…Thin films of molybdenum oxide were deposited on glass substrates using thermal evaporation technique [28][29][30]. MoO 3 powder (99.99 % pure, Sigma Aldrich) as source material was used.…”

Chalcogenide Photonic Crystals Fabricated by Soft Imprint‐Assisted Photodoping of Silver

“…The patterns formed in the ChG film have the same resolution as those on the stamp. While the photodoping of Ag has been reported to modify various ChG materials such as GeS 3 , As 2 S 3 , and GeSbTe, [29,30] the As 2 S 3 film was chosen to demonstrate the IL-SD process. Essentially, when illuminated by UV light with the photon energy greater than the bandgap of As 2 S 3 (E g = 2.7 eV), the As 2 S 3 film absorbs the light, generating electron-hole pairs.…”