Thickness dependence of optical properties of sputtered AZO film on borosilicate glass

Abstract

Abstract Sputtered AZO film with different thicknesses (98, 141, 206, 249 and 306 nm) was deposited on a borosilicate substrate. The XRD pattern indicated that the deposited AZO films showed the prominent peak of the AZO phase in the (002) direction, and the (004) plane was also observed on the 141, 206, 249 and 306 nm films. The peak intensity was increased with film thickness. AFM images reveal that all films show a granule surface and columnar structure with different sizes and distributions depending on thickness. In addition, the surface roughness and electrical resistance of the films were increased with increasing thickness. The 98 nm film exhibited a constant transmission, but the optical transmission of the rest of the films fluctuated with the wavelength in the 400-1000 nm range, and their transmission was thickness-dependent. The maximum mobility and carrier concentration was observed on the 306 and 249 nm, respectively. The energy bandgap of the film ranged from 3.5-3.6 eV and was increased with the film thickness. The results attribute that the thickness significantly modifies structural phase, surface morphology, and roughness, strongly affecting the optical properties of sputtered AZO films.