Annealing effect on morphology, surface roughness and structure of thermally evaporated tin oxide thin films

Abstract

SnO₂ thin films were produced utilizing the Thermal Vacuum Evaporation method on quartz substrates. Three samples—FAA, FV-200, and FA-400—were made and labelled. While samples of the FV-200 and FA-400 were annealed at 200 ^◦C and 400 ^◦C, respectively, the as deposited thin film is FAA. The root mean square (RMS) roughness, uniformity, and average roughness of the films were all measured using the atomic force microscope. The film was spherical after being annealed at 400 ^◦C, covering the substrate more uniformly with erratic growth. The as-deposited film exhibits an uneven distribution of grains of varying sizes. The sample showed consistent grain development after being annealed at 200 ^◦C. The root mean square values of samples FAA, FV-200, and FA400 are 42.2 nm, 41.7 nm, and 112.7 nm. The XRD technique was used to the strongest of which could be seen at 2θ = 300, or the (200) plane of Sn metal. The thin film was annealed in vacuum at 200 ^◦C and revealed three more peaks, with the strongest peak appearing at 2θ = 30^◦, which is consistent with an enhanced structure of Sn metal thin film. The sample annealed at 400 ^◦C revealed high surface roughness compare to other samples and its films are clearly defined, spherical, and cover the substrate more evenly. Whereas, a mixture of large and small grains with uneven distribution throughout the substrate and poor film homogeneity was reveal by film without heat treatment.