Electrical and photoelectrical properties of vacuum deposited SnSe thin films

Polycrystalline thin films of tin selenide have been prepared by vacuum dep osition at a substrate temperature of 150 degreesC and reported. X-ray diff raction, optical transmission, electrical conductivity and photoconductivit y studies have been carried out on these films. Annealing the films at 300 degreesC for 2 hours improves the crystallinity and a preferred orientation along the (111) plane develops. The optical transmission measurement revea ls that the SnSe thin films have a direct allowed band gap of 1.26 eV. Elec trical conductivity study shows that the conductivity increases with increa sing temperature. The observed electrical conductivity at low temperature i s explained based on hopping conduction mechanism. The photoconductivity me asurement indicates the presence of continuously distributed deep localised gap states in this material.