ELECTRICAL TRANSPORT PROPERTIES OF THERMALLY EVAPORATED ZINC SELENIDE (ZnSe) THIN FILMS

摘要

Thin films of Zinc Selenide (ZnSe) of various thicknesses have been deposited onto glass substrates using thermal evaporation technique at room temperature and elevated temperatures. The structural property of the films was studied by X-ray diffraction method and found to be polycrystalline in nature. From the electrical studies of the films it was seen that the as-deposited films were unstable. The films were annealed in vacuum and subjected to several heating and cooling cycles (at temperature rate 5 K/min) up to a temperature of 523 K. From the reproducible resistivity-temperature characteristic, the proper annealing condition was attained. It is found that electrical conductivity of the stabilized ZnSe films increases with increase of substrate temperature upto 453 K and it was about 27×10-4 ohm-1 m-1. The dark electrical resistivity calculations were carried out at different temperatures in the range 298-393 K. The current density-voltage characteristics of ZnSe film at room temperature showed ohmic conduction mechanism at low voltages. At higher voltages the spacecharge limited conduction (SCLC) accompanied by an exponential trap distribution was dominated. Transport properties of the material at ambient temperature have been obtained from the analysis of the samples in the ohmic and SCLC regions.