Optical and Electrical Properties of CdS thin films prepared by spray pyrolysis
Dr. Yashwantrao D Tembhurkar, Mr. Anil S. Meshram, Dr. Omprakash P Chimankar
A thin film of CdS is a semiconducting material for the use in the fabrication of hetero-junction solar cell. Spray pyrolysis is a simple, cheap and inexpensive method of depositing thin films of large area. We have deposited thin films
of CdS on glass substrate at 300 0c by this method, using aqueous solutions of cadmium chloride and thiourea and from the reflectance and
transmittance studies the band gap energy (Eg) is calculated 2.47 eV and has a very high absorption coefficient near the band edge which
shows the direct allowed transition of CdS thin films. The resistivity of the films was measured for temperature ranging from 313 0K to 573 0K.
The activation energy values were calculated from Arrhenius plot; Shallows levels arising from internationals cadmium or sulphur vacancies
are found to extrinsic conductivity near room temperature where as deep trap states influence at higher temperature.