Reference of Temperature and Time during tempering process for non-stoichiometric FTO films

Abstract

In order to enhance the mechanical strength of Low-E glass, Fluorine-doped tin oxide (FTO) films have to be tempered at high temperatures together with glass substrates. The effects of tempering temperature (600°C∼720°C) and time (150s∼300s) on the structural and electrical properties of FTO films were investigated. The results show all the films consist of non-stoichiometric, polycrystalline SnO2 without detectable amounts of fluoride. 700°C and 260s may be the critical tempering temperature and time, respectively. FTO films tempered at 700°C for 260s possesses the resistivity of 7.54×10-4 Ω•cm, the average transmittance in 400∼800nm of ∼80%, and the calculated emissivity of 0.38. Hall mobility of FTO films tempered in this proper condition is mainly limited by the ionized impurity scattering. The value of [O]/[Sn] at the film surface is much higher than the stoichiometric value of 2.0 of pure crystalline SnO2.