Effect of substrate temperature on structural, morphology and optical properties of RF magnetron sputtered CZT thin films

Abstract

Cadmium zinc telluride (CdZnTe) or CZT, a direct band gap semiconductor is used in a variety of applications such as radiation detectors, photo refractive gratings, solar cells and electro-optic modulators. In the present investigation, we have studied the influence of substrate temperature on the structure, morphology and optical properties of radio frequency magnetron sputtered cadmium zinc telluride (Cd_0·4Zn_0·1Te_0·5) thin films deposited onto well cleaned glass substrates. CZT thin films of different thicknesses in the range from 128 to 549 nm with stoichiometric composition were prepared by optimising the process parameters. Transmittance spectra of thin films were recorded using UV-vis spectrophotometer in the wavelength range of 200 to 1500 nm and the optical band gap was determined. Surface topography of CZT thin films was analysed using atomic force microscopy and the root mean square roughness was determined. X-ray diffraction and transmission electron microscopy analysis revealed the presence of zinc blende structure exhibiting the predominant (111) and other planes along (220) and (311) directions. The d-spacing and crystallite size were also calculated. The results are discussed.

Keywords:

• CZT thin films
• RF magnetron sputtering
• Substrate temperature
• Solar cells

Acknowledgements

The authors thank T. Vijayaragavan and K. K. Karthikeyan of PSG Institute of Advanced Studies and M. R. Venkatraman of Coimbatore Institute of Technology for their technical support in carrying out this research work. The authors would like to thank the Principal and Management of PSG College of Technology for supporting the work.