Light scattering through multi-textured periodic glass surface morphologies for a-Si thin film solar cells

Abstract

Front transparent conductive oxide (TCO) films play a vital role in amorphous silicon based thin film solar cells due to their high transparency, conductivity and excellent light scattering properties. The precise surface morphology with better step coverage for the front TCO films is a hot research topic now a days. Since the low step coverage of TCO films suffered non uniformity and hence low performance of amorphous silicon thin film solar cells (a-Si TFSCs). We report novel multi-textured periodic textured glass surface morphologies with high transmittance and better step coverage of AZO films for the a-Si TFSCs. The SF6/Ar plasma etching of glass substrates was used for the high roughness and haze ratio while wet (Buffered Hydro Fluoric acid (BHF)) chemical etching was performed for the better step coverage by controlling the shape of textured glass surface morphology. The pyramid shaped textured glass surface morphologies offered the lowest sheet resistance, high transmittance and roughness for the RF magnetron sputtered AZO films. The AZO films showed the highest total transmittance and haze ratio of 90.19% and 54.29% in the visible wavelength region with lowest sheet resistance of 6.242 Ω/□ for 800 nm thickness. The AZO films deposited on the pyramid glass surface showed the better step coverage. The minor variation in sheet resistance and resistivity of the AZO films was related to the step coverage of the AZO films that is closely related with the shape and angle of the surface morphology. The AZO films with low sheet resistance, high transmittance and step coverage can be employed to improve the performance of future a-Si thin film solar cells.