Evidence for insulator–metal transition in amorphous chalcogenide Se–Ge–Te films

Abstract

The temperature dependence of the dc conductivity and thermoelectric power was determined for five different amorphous chalcogenide Se-Ge-Te films, with Ge ¼ 3.0-22 at.%, Se ¼ 0-97 at.% and Te ¼ 0-97 at.%. The films were prepared by thermal evaporation of GeSe 4 , GeTe 4 and GeSe 2 Te 2 quenched bulk materials. Values of the activation energy calculated from the temperature dependence of both electrical conductivity and thermoelectric power showed a decrease with increasing Ge content in the Se-Ge films as well as with replacement of Te for Se in the Se-Ge-Te films. The results showed an Anderson transition, with the conductivity showing insulating behaviour on the Ge-Se side to metallic behaviour at the binary composition Ge-Te. The radius of localization was obtained for the different compositions investigated. The wave function associated with the charge carriers at the composition Ge 3.3 Te 96.7 is non-localized. A minimum metallic conductivity of 237 AE 5 ( cm) À1 was found.

Application the reduced method for Characterization the photonic properties of amorphous Se 79.13 S 11.41 Te 9.64 Nano thin film composition Part(I)

“…, the relative error of k is calculated by differentiation equation ( 9), where , t and  are the errors in , t and , the relative error of k, k/k = 0.005 Solving equation ( 4) for the refractive index n equation ( 10) obtained [15]: energy respectively [20]. Figure (5) shows that T+R <1 at  <770 nm This is because the absorption of light by the thin film composition. Figure ( 5) also, show that T+R>1 at wavelength range 720 nm.…”

“…technological applications as electronic devices [2], photonics, IR transmissions electronics and optoelectronics industry [3,4]. Also, chalcogenide elements Se, S, and Te, form a class of materials called inorganic polymers [5][6]. These elements when melted together form solid solution composed of Se -Te in Sulphur and S -Te in selenium [7].…”