Effect of Sb additive on the electrical properties of Se–Te alloy

Electrical measurements have been carried out on a-Se85−xTe15Sbx (x = 0, 2, 4, 6 and 10 at.%) thin films. The dark conductivity (σd), photoconductivity (σph) increase and activation energy (ΔEd) decreases as the concentration of Sb additive increases (upto 4 at.%). Photosensitivity (σph/σd) decreases sharply after Sb incorporation. The charge carrier concentration (nσ) is calculated with the help of dc conductivity measurements and its value increases with Sb incorporation. A reverse in the trend takes place in all these parameters as the Sb concentration is further increased (>4 at.%). The results are explained on the basis of increase in the density of localized states present in the mobility gap of Se–Te–Sb alloys.