The microstructure of Al-doped ZnO thin films by a sol-gel dip-coating method

These days, thin film metal oxide semiconductor have been intensively studied for optical and electronic device applications. As a II-VI compound semiconductor, zinc oxide (ZnO) is a wide band gap semiconductor (E_g = 3.3 eV) at room temperature with a Wurtzite crystal structure. In particular ZnO can be employed as the transparent conducting oxide (TCO) in solar cell applications due to its advantages of low cost, high productivity, and excellent electrical conductivity. In this paper, aluminum doped zinc oxide polycrystalline thin films (AZO) have been prepared on glass substrates by a sol-gel dip-coating process. The quantity of aluminum in the solution was 1.0 at.%. After deposition, the films were pre-heated at 350 °C for 10 minutes and then the films were inserted in a furnace and post-heated at 500, 550, 600, 650, 700 °C for 1.5 h. We investigated the structural and microstructural properties of AZO thin film through X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis, respectively. Also we studied the electrical resistance and transmittance of specimens to employ for TCO applications.