Optical properties of thermally vacuum evaporated thin films

Abstract

Silver antimony diselenide thin films were prepared by a thermal vacuum evaporation technique onto quartz and glass substrates kept at room temperature . The as-deposited films were amorphous and transformed to a face centred cubic (FCC) polycrystalline nature with the lattice constant on post-deposition annealing above 423 K for one hour in argon atmosphere. The optical constants (the refractive index n, and the absorption index k) of the films were determined for several samples of different thickness (180 nm-270 nm), using spectrophotometric measurements of the transmittance T and reflectance R at normal incidence in the spectral range 500-2500 nm. These constants were also determined for preannealed films, (polycrystalline). The obtained values of both n and k were independent of the film thickness within the above-mentioned thickness range. The refractive index data fitted a single-oscillator model with high-frequency dielectric constants increasing from 13 for the amorphous films to 15 for the crystalline films. It was found that the high-frequency dielectric constant has the same values as the lattice dielectric constant . The analysis of the spectral behaviour of the absorption coefficient in the intrinsic absorption region revealed the existence of an indirect allowed optical transition with energy gap 1.2 eV for amorphous films and 1.03 eV for the crystalline films, respectively.

Influence of Doping on Structural and Thermoelectric Properties of AgSbSe2

“…Measurement of diffuse reflectance in AgSbSe 2 and AgSbTe 2 provided the evidence of the apparent bandgap (of about 1.03 eV 6 and 0.35 eV 7 for AgSbSe 2 and AgSbTe 2 , respectively), whereas electrical conductivity measurements at room temperature 5 suggested semimetallic behavior of both compounds. de Haas-van Alphen effect measurements show that AgSbTe 2 is a semiconductor with a very narrow energy gap of approximately 7 meV, but according to the authors, it can be considered as an indirect zero-gap material above 100 K. 8 On the other hand, we have recently found that homogenous and isostructural AgSbSe 2 -AgSbTe 2 solid solutions exhibit evident semiconducting temperature dependence of electrical conductivity 9 (E g % 0.3 eV).…”

Crystal structure, electronic and transport properties of AgSbSe2 and AgSbTe2

“…Alloys of both compounds either in single-crystal form or in thin-film form have received considerable interest owing to their optical and electronic properties. They are attractive phase-change (PC) materials used as a switching medium in rewritable optical memories [4][5][6][7][8][9][10][11].…”

Spectroscopic investigations of polycrystalline InxSb20−xAg10Se70 (0 ⩽ × ⩽ 15) multicomponent chalcogenides

“…[12] without denomination of other phases due to their large intensity. The addition of small amount of indium additive (x = 5) results in a decrease in the intensity of diffraction peaks of AgSbSe 2 without forming new phases.…”

“…An addition of a third element usually affects the properties of chalcogenide semiconductors by creating compositional and configurational disorder in the material with respect to binary alloys [11]. Ag-Sb-Se is a narrow band gap p-type * E-mail: prafiziks@gmail.com semiconducting system which crystallizes to AgSbSe 2 with a cubic NaCl type structure [12]. Further, the incorporation of indium in Sb-Se system is expected to make it more suitable for reversible optical recording having less erase time [13].…”