Beneficial effects of hydrogen peroxide on growth, structural and electrical properties of sprayed fluorine-doped SnO2 films

Abstract: Fluorine doped SnO2 thin films were spray deposited using three tin precursors, tin tetrachloride, dibutyl-tin-diacetate and butyl-tin-trichloride, adding small amounts of hydrogen peroxide (H2O2) to the source solutions. The molar ratio range [H2O2]/[Sn]=0 to 0.8 with respect to the tin precursor was investigated. At a given deposition temperature T d, a net optimum was found close to [H2O2]/[Sn]=0.5 for the deposition rate, the electrical properties and the crystalline quality. The effect of H2O2 addition was found to increase the growth rate, even at a temperature as low as 340 °C. The higher was the deposition temperature T d, the larger was the increase. The deposition process of FTO films was optimized at T d =420 °C. At this temperature, the most significant result with respect to solar cell applications was obtained with butyl-tin-trichloride as tin precursor and [H2O2]/[Sn]=0.6; carrier concentration : 4.5×1020 cm−3; mobility : 34 cm2 V−1 s−1; resistivity: 4.1×10−4 Ω cm. It is concluded that the main effect of addition of hydrogen peroxide is to improve the film crystallization at a lower T d than in the absence of H2O2, increasing the carrier mobility significantly and keeping a high deposition rate. [Copyright &y& Elsevier]