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Abstract In this work, TiO₂thin films deposited by the atomic layer deposition (ALD) method were treated with a special N₂O plasma surface treatment and used as the gate dielectric for AlGaN/GaN metal insulator semiconductor high electron mobility transistors (MISHEMTs). The N₂O plasma surface treatment effectively reduces defects in the oxide during low-temperature ALD growth. In addition, it allows oxygen atoms to diffuse into the device cap layer to increase the barrier height and thus reduce the gate leakage current. These TiO₂films exhibit a dielectric constant of 54.8 and a two-terminal current of 1.96 × 10⁻¹⁰A mm⁻¹in 2μm distance. When applied as the gate dielectric, the AlGaN/GaN MISHEMT with a 2μm-gate-length shows a high on/off ratio of 2.59 × 10⁸and a low subthreshold slope (SS) of 84 mV dec⁻¹among all GaN MISHEMTs using TiO₂as the gate dielectric. This work provides a feasible way to significantly improve the TiO₂film electrical property for gate dielectrics, and it suggests that the developed TiO₂dielectric is a promising high-κgate oxide and a potential passivation layer for GaN-based MISHEMTs, which can be further extended to other transistors. 

In this work, we report high performance GaN-on-Si Metal Insulator Semiconductor High Electron Mobility Transistors using TiAlOand HfZrO as the gate dielectric. We take the advantages of the high dielectric constant TiO2 and high bandgap Al2O3, achieving a low gate leakage current and simultaneously an excellent gate control capability. Ti and Al composition effect on the DC performance is investigated. A HfZrO gate dielectric is also utilized as a reference. fT/fmax of 150/206GHz and 150/250GHz were respectively achieved on TiAlO and HfZrO GaN-on-Si MISHEMTs. Device power performance is also evaluated. 

In this work, we report high performance GaN-on-Si Metal Insulator Semiconductor High Electron Mobility Transistors using TiAlOand HfZrO as the gate dielectric. We took the advantages of the high dielectric constant TiO2 and high bandgap Al2O3, achieving a low gate leakage current and simultaneously an excellent gate control capability. Ti and Al composition effect on the DC performance is investigated. A HfZrO gate dielectric is also utilized as a reference. fT/fmax of 150/206GHz and 150/250GHz were respectively achieved on TiAlO and HfZrO GaN-on-Si MISHEMTs. Device power performance is also evaluated.