Electrical and optical properties dependence on evolution of roughness and thickness of Ga:ZnO films on rough quartz substrates

The paper studies GZO films deposited on quartz substrates by a laser deposition system. The XRD and AFM results as well as the calculation of height–height correlation function H (r, t) and its parameters w(t) and ξ(t) reveal that the film growth can be divided into two stages, and that the turning point of these two stages is the time when the film exhibits fractal characteristics. The influence of thickness and morphology roughness evolution on the electrical resistivity and optical transmittance in these two stages are described. It is found that the electrical resistivity mainly depends on the film thickness in the first stage, while in the following stage, the film possess self-affine fractal characteristics. The morphology roughness evolution plays an important role in the resistivity. The transmittance is found to decrease with the increase of film thickness in the two stages and it is also found to be sensitive to the evolution of surface roughness. The lowest resistivity obtained is 4.85 × 10− 4 Ω cm with an average optical transmittance of 85% in the 200 nm thick film deposited for 10 min.