On thickness dependence of electrical and optical properties of Te thin films

Abstract

The thickness dependences of electrical conductivity, hole mobility, and optical reflectivity are investigated for Te thin films deposited onto glass substrates by thermal evaporation under vacuum. It is found that with an increasing films thickness, the values of these parameters decrease. This behaviour is interpreted, taking into account the specific polycrystalline structure of studied films. By X-ray diffraction studies it was established that in these films the orientation of crystallites changes with an increase in the film thickness. Consequently, we propose a structural model in which the Te thin films are considered as being formed from two superposed layers: the first layer having a preferred orientation of crystallites with their c-axis parallel to the substrate and the second layer with crystallites obliquely oriented to the substrate. The thickness of these sublayers depends on deposition conditions. This structural model is used to explain the thickness dependences.