High-k HfO2 based AlGaN/GaN MIS-HEMTs with Y2O3 interfacial layer for high gate controllability and interface quality

High- ${k}$ HfO 2 has been widely adopted in Si based MOSFETs as gate dielectric for the superior control over gate leakage and channel electrostatics. However, in AlGaN/GaN HEMTs, the additional interface issue as well as high oxygen transparency of HfO 2 has hindered its practical applications. In this work, high- ${k}~\text{Y}_{2}\text{O}_{3}$ with ultra-low oxygen permeability and high thermodynamic robustness has been introduced as the interfacial layer between HfO 2 /GaN for the interface engineering. It has been demonstrated that, the HfO 2 /Y 2 O 3 gate dielectric stacks have obtained the GaN MIS-HEMT an ultra-small subthreshold swing of ~70 mV/decade, an extremely low gate leakage of ~10 −12 A/mm, and a desirable dielectric/semiconductor interface quality with interface state density in level of ~10 12 cm −2 eV −1 . Meanwhile, a maximum drain current of 600mA/mm has been achieved together with an on-state resistance ( ${R} _{\mathrm{ on}}$ ) of 10.7 ${\Omega }\cdot $ mm and a specific ${R} _{\mathrm{ on}}$ of 2.62 $\text{m}{\Omega }\cdot $ cm 2 .