Synthesis of high-quality AZO polycrystalline films via target bias radio frequency magnetron sputtering

Abstract

The deposition rate, transmittance and resistivity of aluminium-doped zinc oxide (AZO) films deposited via radio frequency (r.f.) sputtering change with target thickness. An effective method to control and maintain AZO film properties was developed. The strategy only involved the regulation of target bias voltage of r.f. magnetron sputtering system. The target bias voltage considerably influenced AZO film resistivity. The resistivity of the as-deposited AZO film was 9.82×10−4Ωcm with power density of 2.19W/cm2 at target self-bias of −72V. However, it decreased to 5.98×10−4Ωcm when the target bias voltage was increased to −112V by applying d.c. voltage. Both growth rate and optical band gap of AZO film increased with the absolute value of target bias voltage – growth rate increased from 10.54nm/min to 25.14nm/min, and band gap increased from 3.57eV to 3.71eV when target bias voltage increased from −72V to −112V at r.f. power density of 2.19W/cm2. The morphology of AZO films was slightly affected by the target bias voltage. Regulating target bias voltage is an effective method to obtain high-quality AZO thin films deposited via r.f. magnetron sputtering. It is also a good choice to maintain the quality of AZO film in uptime manufacturing deposition.