Improved Performance of Stair-Stepping Buffer-Gate 4H Silicon Carbide Metal Semiconductor Field Effect Transistor

摘要

The 4H SiliconCarbide metal semiconductor field effect transistor (4H-SiC MESFET) with a buffer layer between the gate and channel (BG) is optimized and a new stair-stepping buffer-gate structure (SBG) is proposed for improving the breakdown characteristics. The terminal technology of breakdown point transfer (BPT) is applied in 4H-SiC SBG-MESFET in order to scatter the electric field lines and transfer the breakdown point. The breakdown mechanism is further investigated by simulating the surface electric field distribution and electrostatic potential contours. The results show that the breakdown voltage is increased from 120 V to 180 V, improved by the rate of 50% while the current density has hardly deteriorated, and thus the current density is improved from 9.35 W/mm to 13.2 W/mm in comparison with BG structure.