Effects of hydrogen flux on aluminum doped zinc thin films by pulsed magnetron sputtering

Aluminum doped zinc oxide (AZO) thin films are prepared by pulsed magnetron sputtering in pure argon gas. In order to improve the properties of AZO thin films, we add hydrogen gas into vacuum during sputtering. High purity ceramic ZnO ∶Al2O3 target and hydrogen gas at various flow rates are used as source materials. The microstructure, the surface information, the optical and electrical properties of AZO/H film are investigated. The crystallization, the Hall mobility and the transmission between 400 nm and 1100 nm are enhanced by increasing H2 flow rate, and resistivity is decreased, the lowest resistivities of these films are all 4.435×10-4 Ω·cm, and AZO thin films with 5.664×10-4 Ω·cm are achieved. In this experiment, it is observed that Raman peak is related to defects due to O-vacancies (579 cm-1) in the AZO/H thin films grown at different H2 flow rates. With the increase of hydrogen flow rate, the intensity of Raman peak at 579 cm-1 decreases. Finally, AZO and AZO/H thin films are etched in 0.5% dilute hydrochloric acid. Compared with AZO thin films, AZO/H thin films can be relatively easy to achieve the light trapping structure with crater-type morphology.