【International Papers】Low resistance Ohmic contact of multi-metallic Mo/Al/Au stack with ultra-wide bandgap Ga₂O₃ thin film with post-annealing and its in-depth interface studies for next-generation high-power devices

      Researchers from the Indian Institute of Technology Ropar have published a dissertation titled "Low resistance Ohmic contact of multi-metallic Mo/Al/Au stack with ultra-wide bandgap Ga₂O₃ thin film with post-annealing and its in-depth interface studies for next-generation high-power devices " in Surfaces and Interfaces.

Abstract

      Ultra-wide band gap materials like β-Ga₂O₃ is considered as a potential candidate for power devices owing to their high breakdown voltage in contrast to the conventional semiconductors. The performance and the figure-of-merit for power devices critically depend on resistance offered by ohmic contact of metal with ultra-wide gap materials. However, high-quality ohmic contacts with Ga₂O₃ presents a significant challenge due to Fermi-level pinning and formation of Schottky barriers for the majority of metal contacts. Here, we investigated the electrical characteristics and interfacial reactions of Au/Al/Mo metal stack with β-Ga₂O₃ thin film at various annealing temperatures to demonstrate the ohmic contact formation mechanism. In-depth surface-sensitive XPS and UPS are employed to study the interface of metallic stack/Ga₂O₃ thin film. Our results indicate that post-annealing at high temperatures led to the intermixing of the metallic stack and results in the formation of binary intermetallic compounds of Al and Au. The intermetallic compound diffuses into the Ga₂O₃ layer and resulting in the creation of an oxygen-deficiency near the interface and helping to achieve contact resistance of 7.15 × 10⁻⁶ Ω-cm². This study establishes a robust foundation for the expanded utilization of Ga₂O₃ in power electronics and optoelectronics devices, emphasizing the vital role of interface engineering.

Paper Link：https://doi.org/10.1016/j.surfin.2024.103937