Effect of the tin content on the composition and optical and electrical properties of ITO films deposited onto silicon and glass by ultrasonic spray pyrolysis

With the aim of optimizing the properties of tin-doped indium oxide (ITO) films as applied to silicon solar cells, $\sim$100-nm-thick ITO films were deposited onto $(nn^+)$-Cz-Si and glass substrates by ultrasonic spray pyrolysis in argon at a temperature of 380$^\circ$C. The relative Sn and In content in the film-forming solution was varied in the range of [Sn]/[In] = 0–12 at%. Optimal parameters are exhibited by the films produced at [Sn]/[In] = 2–3 at% in the solution ([Sn]/([In] + [Sn]) = 5.2–5.3 at% in the film). For such films deposited onto glass substrates, the effective absorptance weighted over the solar spectrum in the wavelength range from 300 to 1100 nm is 1.6–2.1%. The sheet resistance $R_s$ of the films deposited onto silicon and glass is, correspondingly, 45–55 and 165–175 $\Omega\square^{-1}$. After eight months of storage in air, the resistance $R_s$ of the optimal films remained unchanged; for the other films, the resistance $R_s$ increased: for the films on silicon and glass, the resistance $R_s$ became up to 2 and 14 times higher, respectively.