화학공학소재연구정보센터
Thin Solid Films, Vol.569, 17-21, 2014
Physico-chemical properties of the thin films of the SbxSe100-x system (x=90, 85, 80)
The bulk samples of SbxSe100 -x system (x = 90, 85, 80) and their amorphous thin films were prepared by flash evaporation method. The films possess good thermal stability and high values of the activation energy of crystallization. The activation energy of crystallization (E-a) of the thin films Sb85Se15 and Sb80Se20 was found to be 2.97 and 2.55 eV, respectively. The E-a of Sb90Se10 was found to be 1.79 eV for first step and 2.95 eV for second step. The homogeneous thin amorphous films were crystallized by nanosecond laser pulses, by annealing at 235 and 360 degrees C and during the measurement of temperature dependence of electrical resistivity. The crystalline phase possesses much lower electrical resistivity than the amorphous one (Delta R-s approximate to 10(3)); the temperature of crystallization T-c is from the region of 150-161 degrees C. The structure of prepared films as determined by X-ray diffraction analysis revealed that the films crystallized by laser pulses and by annealing at 235 degrees C contain only one phase of Sb-like structure. The films of composition Sb80Se20 and Sb85Se15 annealed at 360 degrees C contain two phases of Sb and Sb2Se3. The film of composition Sb90Se10 annealed at 360 degrees C contains one phase of Sb-like structure. The optical reflectivity change due to crystallization is also large (Delta R-opt. approximate to 20-30%). The refractive index n of crystalline samples is higher than that of amorphous films (Delta n approximate to 1.5-3.1 for transparent part of spectrum); it is higher for films with higher Sb content. The real and imaginary parts of permittivity, evaluated from ellipsometric measurement, are also much higher for crystalline state (up to 55) than for the amorphous one (<33). The amorphous films are semiconductive, and their E-g(opt.) (0.28-0.35 eV) is decreasing with an increasing content of Sb. In spectral region of lambda= 360-830 nm, the real part of permittivity of crystalline phase is negative and the imaginary part of permittivity is not high, especially for the Sb90Se10 samples. Such films are perspective not only as the phase change materials, but also as the plasmonic materials. (C) 2014 Elsevier B.V. All rights reserved.