Textured fluorine-doped ZnO films by atmospheric pressure chemical vapor deposition and their use in amorphous silicon solar cells

Abstract

Fluorine-doped ZnO films were deposited on soda lime glass by atmospheric pressure chemical vapor deposition at temperatures from 350 to 470 °C by using diethyl zinc, ethanol and hexafluoropropene as precursors. The deposited films typically contained about 0.1 to about 1.0 at.% fluorine with conductivities up to 2500 ω⁻¹ cm⁻¹. The free electron concentrations determined from Hall coefficient measurements were up to $\text{5 × 10}{}^{20}\text{cm}{}^{\mathrm{-3}}$ and the mobilities were between 10 and 40 cm² V⁻¹ s⁻¹. The films with very low sheet resistances of 5 ω/□ were found to have visible absorption of only 3% and transmittance up to 90% in the visible and reflectance of about 85% in the infrared. The film roughness was controlled by the deposition temperature and by introducing a small amount of water vapor. The rough films were used as substrates for amorphous silicon solar cells with very high quantum efficiency (up to 90%).