Influence of texture coefficient on the electrical properties of spray-deposited fluorine-doped tin oxide thin film

Abstract

Fluorine-doped tin oxide (FTO) thin films were deposited onto a glass substrate using the spray pyrolysis technique, and the substrate temperature was varied from 450 to 550 °C with steps of 25 °C. A considerable change was observed for the texture, which was found to be influential on the morphological and electrical characteristics of the FTO thin films. Although the FTO film deposited at 450 °C was highly textured along the (200) orientation, a considerable reduction was observed for TC(200) after 500 °C. On the contrary, the TC(301) and TC(200) started to grow by increasing the substrate temperature to the extent of being the completely dominant planes at 550 °C. As a result, the mobility of the films met a constant reduction from 24.20 cm² V⁻¹ s⁻¹ for 450 °C to 11.40 cm² V⁻¹ s⁻¹ for 550 °C. The carrier concentration reached its maximum at 500 °C (3.86 × 10²⁰ cm⁻³) and declined with a further increase of the deposition temperature. The best resistivity of 8.25 × 10⁻⁴ Ω cm corresponding to a 16 Ω/sq sheet resistance and average transmittance of 85.32% was achieved at 500 °C. The aforementioned results led to a considerable figure of merit of 12.8 × 10⁻³ Ω⁻¹ which is indicative of a high-quality spray-deposited FTO thin film.