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 Y 2 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 on ) of 10.7 Ω·mm and a specific R on of 2.62 mΩ·cm 2 .