Effect of growth temperature on the structural and optical properties of CdS:O thin films for CdTe solar cells

Abstract

Oxygenated Cadmium Sulfide (CdS:O) is used as a window layer for high-performance CdTe thin-film solar cells. In this work, the effect of growth temperature on the physical properties of (CdS:O) layer is reported. The CdS:O layer was synthesized on commercially available soda-lime glass (SLG) by using a reactive radio frequency (RF) sputtering in 1.5% oxygen (O2)/argon (Ar) ambient as a function of substrate temperature (25 °C to 300 °C). The structural and optical properties of the as-grown CdS:O thin films were carried out by X-ray diffraction and UV-VIS-Spectroscopy respectively. The XRD patterns revealed intriguing structural natures of the deposited films such as amorphous/semi-amorphous nature in the substrate temperature range 25-150 °C, then polycrystalline nature in the range 200-250 °C and again amorphous nature at 300 °C. The transmission spectra exhibited higher optical transmission in the visible wavelength which signifies the enhancement of photo generated current of CdTe solar cells. The bandgap of room temperature (RT) deposited CdS:O thin film for 1.5% O2/Ar was found to be increased 12.50% in comparison with CdS film deposited in pure Ar ambient. Besides, the bandgap of CdS:O films for 1.5% O2/Ar was decreased with the increase of the substrate temperature. Thus, it has been concluded that the CdS:O thin film deposited at RT found to be better for CdTe solar cell application. © 2019 IEEE.