Enhanced band-tuning and quality of Ni-doped Ga2O3 films via low-power RF magnetron sputtering

Abstract

Low power density radio-frequency (RF) magnetron sputtering of Ni-doped gallium oxide (Ga₂O₃) films offers notable advantages in terms of improved film quality and realizable band-tuning. In this research, the Ni-doped Ga₂O₃ films are deposited on a substrate using RF magnetron sputtering at different powers of 70–140 W. The effects of low sputtering power on the optical and chemical properties of Ni-doped Ga₂O₃ films are studied. The experimental results illustrate that an effective Ni doping is observed at higher than 100 W as shown by the obvious increase in the intensity of the Ni plasma radicals and the Ni atomic ratio. The Ni-doped Ga₂O₃ film prepared at 120 W reveals a larger cluster size and maximum ratios of Ni³⁺ and non-lattice oxygen, resulting in the highest values in mobility and carrier concentration of 3.5 cm² V⁻¹ s⁻¹ and 5.0 × 10¹⁶ cm⁻³, respectively. With increasing powers, a decrease in the band gap from 5.2 to 4.8 eV is observed. The RF sputtering of Ni-doped Ga₂O₃ films at a lower power density, ranging from 0.18 to 0.36 W cm⁻², provides an alternative in large-area industrial applications.