Optical and electronic properties of highly stable and textured hydrogenated ZnO:Al thin films

We have experimentally investigated the effects of hydrogen-annealing on the structural, electrical, and optical properties of Al-doped ZnO (ZnO:Al) thin films prepared by RF magnetron sputtering at room temperature. From the X-ray diffraction observations, the orientation of ZnO:Al films was found to be a c-axis in the hexagonal structure. We found that intentionally incorporated hydrogen plays an important role in n-type conduction as a donor, improving free carrier concentration and electrical stability. We simultaneously obtained improved optical transmission and enhanced absorption edge of the ZnO:Al film due to hydrogen-annealing. Our experimental data suggest the hydrogen-annealing process as an important role in the enhancement of electrical and optical properties, which is promising as a back reflector material for thin-film solar cells.