Investigation of Double RESURF P-GaN Gate AlGaN/GaN Heterostructure Field-Effect Transistors with Partial N-GaN Channels

In this paper, a double REduced SURface Field (RESURF) P-GaN gate AlGaN/GaN heterostructure field-effect transistor with a partial N-GaN channel (DR-HFET) is proposed to improve the on-state performance in the high-voltage P-GaN gate AlGaN/GaN heterostructure field-effect transistor (PG-HFET). The partial N-GaN channel between the gate and the drain increases the carrier density in the channel layer, and markedly reduces the on-resistance (R_on). The P-top layer and the P-buffer layer modulate the distribution of the electric field along the GaN channel to achieve a high breakdown voltage. After validation of the simulation models and parameters, the DR-HFETs are optimized using the charge balance principle. The optimum DR-HFET with a gate-to-drain distance of L_gd = 6 μm shows a BV of 1100 V and R_on of 5.5 Ω mm, which is 50.9% of the R_on in PG-HFET. The highest Baliga figure of merit (BFOM) of 2.3 GW/cm² is obtained when the channel charge density Q_ch is 3.2 × 10¹³ cm⁻² and the ratio of the P-top charge density Q_pt to the buffer charge density Q_buf is 1.625. We also examine the influence of the AlGaN/GaN quality on the performance of the DR-HFETs. The simulation results indicate that the double RESURF structure may be less effective in the high-quality AlGaN/GaN epitaxial layer. Overall, the DR-HFET shows a good balance between off-state blocking capability and on-state performance.