Effect of Substrate Temperature on Optical Band Gap and Thickness of Spray Pyrolitically Deposited CdZnTe2 Thin Films

Spray pyrolysis is a simple, inexpensive and economical method to produce a thin film on large substrate area. Semiconducting thin films of CdZnTe2 have been deposited onto preheated glass substrate by varying substrate temperature from 250C at an interval of 25C to 325C. The optimized deposition temperature is around 300C. From optical transmission and reflection spectra, absorption coefficient () was calculated at various wavelengths ranging from 350 nm to 1100 nm and was of the order of 104 cm-1. Band gap energy were determined from absorbance measurement in visible range using Tauc theory. It shows that the main transition at the fundamental absorption edge is a direct allowed transition. At the temperature of 300C, the optical band gap is found to be 2.04 eV. At the temperatures less than or greater than 300C, the optical band gap goes on increasing. The band gap energy value 2.04 eV- 2.13 eV is most suitable for many scientific studies and technological applications such as heat mirrors, transparent electrodes and solar cells. SEM study provide the information regarding the morphology of the material which confirms the formation of nano sized, nanotubes