Demonstration of Complementary Power Circuit With Normally-Off Diamond P-FET and GaN N-FET

We demonstrate a normally-off HfO2/diamond p-FET featuring a high ON/OFF current ratio (ION/IOFF) of 5 ×10¹⁰ and a high Baliga’s figure-of-merit of 10.34 MW/cm². Based on the band alignment between the hydrogen-terminated diamond (H-diamond) and HfO2 extracting from XPS, it is revealed that the gate metal with a low work function can deplete the 2-D hole gas (2DHG) channel in the gate region and enable normally-off operation, whereas the well-accumulated 2DHG in the access region can maintain a relatively low ON-resistance simultaneously. In addition, the normally-off HfO2/H-diamond p-FET exhibits enhanced threshold voltage stability, which is verified by μs-level high-speed pulsed I-V characterizations. For the first time, a complementary power circuit featuring a normally-off diamond p-FET and GaN n-FET with matched conduction capability has been demonstrated. Compared with the counterpart with series connection of n-FETs, the p/n complementary power circuit featuring upper diamond p-FET enables more stabilized gate driving voltage in switching transient, showing great potential for next-generation high-frequency and high-power electronics applications.