Breakdown voltage enhancement in GaN channel and AlGaN channel HEMTs using large gate metal height**Project supported by the National Key Science & Technology Special Project of China (Grant No. 2017ZX01001301), the National Key Research and Development Program of China (Grant No. 2016YFB0400100), and the National Natural Science Foundation of China (Grant Nos. 51777168 and 61801374).

Abstract

A large gate metal height technique is proposed to enhance breakdown voltage in GaN channel and AlGaN channel high-electron-mobility-transistors (HEMTs). For GaN channel HEMTs with gate–drain spacing LGD = 2.5 μm, the breakdown voltage VBR increases from 518 V to 582 V by increasing gate metal height h from 0.2 μm to 0.4 μm. For GaN channel HEMTs with LGD = 7 μm, VBR increases from 953 V to 1310 V by increasing h from 0.8 μm to 1.6 μm. The breakdown voltage enhancement results from the increase of the gate sidewall capacitance and depletion region extension. For Al0.4Ga0.6N channel HEMT with LGD = 7 μm, VBR increases from 1535 V to 1763 V by increasing h from 0.8 μm to 1.6 μm, resulting in a high average breakdown electric field of 2.51 MV/cm. Simulation and analysis indicate that the high gate metal height is an effective method to enhance breakdown voltage in GaN-based HEMTs, and this method can be utilized in all the lateral semiconductor devices.