Impact of doping concentration and recess depth to achieve enhancement mode operation in β-Ga2O3 MOSFET

High power switching applications necessitates the MOSFET to operate in Enhancement mode (normally OFF). Achieving enhancement mode operation in /3-Ga2O3 MOSFET is challenging due to the difficulty in p-type doping. A TCAD simulation study is implemented to study the effect of the variation of doping concentration and recess gate to achieve enhancement mode operation. Subsequently, the device characteristics such as Id-Vd, Id-Vg and breakdown analysis are performed for /3-Ga2O3 MOSFET with a channel thickness of 240 nm. On decreasing the doping concentration, the magnitude of threshold voltage reduces to 0V at a doping concentration of 1 x 1016 cm-3 causing enhancement mode operation but with significantly low drain current. However, this resulted in the increase in the device breakdown voltage. Adding Si3N4 passivation layer, further, enhanced the breakdown voltage. Subsequent study involved the impact of recessed gate to achieve enhancement mode operation. On increasing the recess depth, the magnitude of threshold voltage is reduced to 0V at a doping concentration of 8 x 1017 cm-3 with less impact on drain current. This also resulted in the increase in the device breakdown voltage. The obtained results will be instrumental for Ga2O3 community to develop and design enhancement mode /3-Ga2O3 MOSFET for high power and high voltage applications.

Automated summary

In this study, TCAD simulations were performed to investigate the effects of varying doping concentration and recess gate on the enhancement mode operation of /3-Ga2O3 MOSFETs. Lowering the doping concentration reduced the threshold voltage to 0V, enabling enhancement mode operation but leading to significantly reduced drain current. The addition of a Si3N4 passivation layer further increased the breakdown voltage. These findings are important for the development and design of enhancement mode /3-Ga2O3 MOSFETs for high power and high voltage applications.