**Chi-Fan Liu 1, Chun-Hsien Kuo 2, Tao-Hsing Chen 1,\* and Yu-Sheng Huang <sup>1</sup>**


Received: 20 March 2020; Accepted: 13 April 2020; Published: 16 April 2020

**Abstract:** Ti-doped SnO2 transparent conductive oxide (TCO) thin films are deposited on glass substrates using a radio frequency (RF) magnetron sputtering system and then are annealed at temperatures in the range of 200–500 ◦C for 30 min. The effects of the annealing temperature on the structural properties, surface roughness, electrical properties, and optical transmittance of the thin films are then systematically explored. The results show that a higher annealing temperature results in lower surface roughness and larger crystal size. Moreover, an annealing temperature of 300 ◦C leads to the minimum electrical resistivity of 5.65 <sup>×</sup> 10−<sup>3</sup> <sup>Ω</sup>·cm. The mean optical transmittance increases with an increase in temperature and achieves a maximum value of 74.2% at an annealing temperature of 500 ◦C. Overall, the highest figure of merit (ΦTC) (3.99 <sup>×</sup> 10−<sup>4</sup> <sup>Ω</sup>−1) is obtained at an annealing temperature of 500 ◦C.

**Keywords:** SnO2; Ti-doped; annealing temperature; electrical resistivity; transmittance
