High-Voltage Normally-off Recessed Tri-Gate GaN Power MOSFETs With Low on-Resistance

In this letter, we present normally-off GaN-on-Si MOSFETs based on the combination of tri-gate with a short barrier recess to yield a large positive threshold voltage (VTH) while maintaining a low specific on resistance (RoN,sP) and high current density (ID). The trigate structure offered excellent channel control, enhancing VTH from +0.3 V for the recessed to +1.4 V for the recessed tri-gate, along with a much reduced hysteresis in VTH, and a significantly increased transconductance (gm). Additional conduction channels at the sidewalls of the tri-gate trenches compensated the degradation in oN-resistance (RoN) from the gate recess, resulting in a small RoN of 7.32 0.26 52mm for LGD of 15 juill and an increase in the maximum drain current (,pax). In addition, the tri-gate inherently integrates a gate-connected field-plate (FP), which improved the breakdown voltage (VBR) and reduced the degradation in dynamic RoN. With proper passivation techniques, these devices could be very promising as high-performance power switches for future power applications.