Aluminum Doped Zinc Oxide via Facile Pneumatic Spray Pyrolysis for Photovoltaic Applications

Undoped and Aluminum-doped Zinc Oxide (AZO) were grown on a glass substrate using a facile home developed pneumatic spray pyrolysis technique. Four samples were prepared with Aluminum percentage weight ratios of 0, 0.5, 0.75 and 1. The structural, electrical and optical properties of the grown films were characterized using X-ray diffraction (XRD), the four-point and Ultraviolet–visible (UV-vis) spectroscopy methods respectively. XRD characterization revealed that the undoped and doped Zinc Oxide (ZnO) films have a polycrystalline structure with a strong preferential growth orientation along the (002) direction and the crystallite size increases and then decrease and ranges from 31.66 to 84.93 nm indicating the reduction increase again of defects. UV-vis spectroscopy has shown that the 0.1 % Al portion slightly enhanced the film transmission while larger amounts drastically deteriorated it which is probably due to the behavior of defect and the surface roughness. The band gap energy was almost unaffected varying between 3.21 and 3.29 eV. The defect’s behavior has also affected the sheet resistance which showed a huge decrease of for increasing Al ratio until the last ratio where it has slightly increased. Although, most of the obtained results behave in their usual way, the transmittance behavior is the most remarkable where it can be useful in designing solar cells where the lightly doped AZO can be used as a window while the highly doped AZO can be used as part of the heterojunction with a p-type semiconductor (like Si, GaAs or another oxide) to increase generation and collection of carriers.