Impact of film thickness on optical and electrical transport properties of noncrystalline GeSe1.4Sn0.6 films

Abstract

The optical and electrical properties for GeSe1.4Sn0.6 with a different film thickness of 145, 230 and 343nm were studied. Structural properties affirm the amorphous nature of these films at different thickness. Transmittance (T) and Reflectance (R) of these films are measured with different film thickness and then the other optical properties are calculated. The calculated linear optical properties illustrated that the optical band gap, phonon energy, refractive index and dielectric constants of these films are increasing with increasing film thickness. On the other hand, the calculated third-order nonlinear optical susceptibility is found to be a function of the film thickness of GeSe1.4Sn0.6 films. Regarding the electrical properties, both dc electrical conductivity, and current-voltage dependence are studied for GeSe1.4Sn0.6 with different film thickness. The dc electrical conductivity as a function of the temperature is verified the Mott and Davis model. The experimental and calculated results have shown that the present film has two regions on the current-voltage relation. In the ohmic district, the conduction has no traps of electron in the forbidden gap of present films. In the range of higher voltage, the current is expected a limited space charge which controlled by a single trap level.