*3.5. Surface Feature Analysis*

Figures 5 and 6 show AFM and SEM images of the various as-deposited and annealed Ti:SnO2 films. The mean surface roughness values of the films are listed in Table 3. As shown, the as-deposited sample has a surface roughness of 0.31 nm. However, following annealing at 300 ◦C, the surface roughness falls to a value of around 0.35 nm due to the formation of the crystalline phase. However, as the annealing temperature is further increased, the surface roughness reduces and has a value of just 0.296 nm in the sample processed at the highest annealing temperature of 500 ◦C. The AFM and SEM images show that the as-deposited Ti:SnO2 film and the film annealed at 300 ◦C have higher surface roughness. Annealing at a temperature of 300 ◦C results in high roughness, but after 300 ◦C the roughness is decreased.

**Figure 5.** Atomic force microscopy (AFM) images of as-deposited and annealed Ti:SnO2 films: (**a**) as-deposited, (**b**) annealed at 200 ◦C, (**c**) annealed at 300 ◦C, (**d**) annealed at 400 ◦C, and (**e**) annealed at 500 ◦C.

**Figure 6.** SEM images of as-deposited and annealed Ti:SnO2 films: (**a**) as-deposited, (**b**) annealed at 200 ◦C, (**c**) annealed at 300 ◦C, (**d**) annealed at 400 ◦C, and (**e**) annealed at 500 ◦C.

**Table 3.** Effects of annealing temperature on surface roughness of Ti:SnO2 films.

