ZnO:(B, Ga)/Au electrodes for improved Ohmic contacts on ultrawide-bandgap Ga2O3 films

Abstract

Gallium oxide (Ga₂O₃) is an ultrawide-bandgap semiconductor material known for its high breakdown field strength, large Baliga's figure of merit, and significant thermal and chemical stability, making it suitable for advanced technological applications. In this paper, Ga₂O₃ films were prepared using radio-frequency (RF) magnetron sputtering. B and Ga co-doped ZnO (BGZO)/Au composite electrodes were developed to achieve improved Ohmic contact characteristics with Ga₂O₃ films, comparing these results with those of widely used Ti/Au electrodes. The specific contact resistance of the electrodes was quantitatively measured using the dot circular transmission line model (d-CTLM) method. The results indicate that the presence of BGZO intermediate semiconductor layers (ISL) with appropriate thickness effectively reduces the specific contact resistance between the electrode and the Ga₂O₃ film, and the minimum specific contact resistance value is 1.049 × 10⁻² Ω·cm². This research provides critical insights into optimizing electrode to enhance the performance and reliability of Ga₂O₃-based devices.