Surface morphological and optical evolution of RF sputtered AZO films for optoelectronic devices

Herein, aluminium-doped zinc oxide (AZO) films were fabricated onto borosilicate glass and fluorine-doped tin oxide (FTO) substrates by RF sputtering. Surface morphology and scaling studies of these films revealed the formation of large grain in AZO films fabricated onto the glass substrates. Several fractal parameters of all samples have been evaluated to understand the deeper morphological insights of observed surfaces. Optical investigations revealed a higher transmittance of similar to 93% in the visible region for FTO/AZO films. Estimated values of Urbach energy are found to be 0.20 eV and 0.17 eV for glass/AZO and FTO/AZO films, respectively. Important optical constants such as refractive indices, extinction coefficients, etc have been investigated to explore the optical mechanism of these films. Furthermore, photoluminescence studies suggest the reduction in the deep-level emission defect states for AZO films fabricated onto FTO substrate. These results propose that AZO films may be suitable for use in optoelectronics.