*3.7. Figure of Merit(*Φ*TC)*

The figure of merit (ΦTC) is an important factor used to evaluate the performance of TCO films from the relationship between transmittance and electrical properties. The figure of merit (ΦTC) is defined as [36] as follows:

$$
\Phi\_{\rm TC} = T^{10} / R\_{\rm sh} \tag{3}
$$

where *T* is the average optical transmittance, and *R*sh is the sheet resistance of the films. Table 4 shows the figure of merit(ΦTC) results for the as-deposited and annealed Ti:SnO2 thin films. As shown, the optimal <sup>Φ</sup>TC (3.99 <sup>×</sup> 10−<sup>4</sup> <sup>Ω</sup>−1) is obtained at an annealing temperature of 500 ◦C. According to the figure, we see that because of an insignificant difference in electrical properties, it has led to a more obvious influence on quality elements from mean optical transmittance, and the optimal mean transmittance is seen at 500 ◦C. Therefore, optimum quality elements can be achieved at 500 ◦C.


**Table 4.** The figure of merit of Ti/SnO2 (ΦTC (Ω−1)).
