Design of a recessed-gate GaN-based MOSFET using a dual gate dielectric for high-power applications

We have investigated gallium-nitride (GaN)-based metal-oxide-semiconductor field-effect transistors (MOSFETs) having a recessed-gate structure for high-power applications. Recessed-gate GaN-based MOSFETs have been designed with a dual high-k dielectric structure to overcome low current drivability. Compared to recessed-gate GaN-based MOSFETs having a single gate dielectric with the same oxide thickness, recessed-gate GaN-based MOSFETs having a dual high-k dielectric composed of Al₂O₃ and HfO₂ have achieved a high drain current (I_D) and transconductance (g_m) due to the high dielectric constant of HfO₂. Also, because the dual high-k dielectric forms a high electron density in the channel layer with outstanding gate control capability, low channel resistances (R_ch) have obtained. In addition, we have studied the effect of the length between the gate and the drain (L_gd) on the on-resistance (R_on) to minimize the R_on that is associated with power consumption and switching performance. Also, the electric field distribution of a device having a dual high-k dielectric has been examined with a field plate structure for high drive voltage. The proposed device was confirmed to be a remarkable candidate for switching devices in high-power applications.