Design of High Baliga’s Figure-of-Merit P-GaN Gate AlGaN/GaN Heterostructure Field-Effect Transistors with P-AlGaN Field Plates

An experimentally calibrated technology computer-aided design (TCAD) simulation was conducted to study P-GaN gate AlGaN/GaN heterostructure field-effect transistors with gate-connected P-AlGaN field plates (PAFP-HFETs). The P-AlGaN field plates modulated the distribution of an electric field along the GaN channel, suppressed electric field crowding at the edge of the gate, and remarkably improved the breakdown voltage (BV). The PAFP-HFET with a gate-to-drain distance of L_gd = 6 μm, showed a BV of 1560 V with an average breakdown electric field of 2.6 MV/cm. The PAFP with structural parameters of length L_p, thickness T_p, doping density N_P, and gate connected metal length L_m were optimized by the charge balance principle of the RESURF concept. The highest Baliga figure-of-merit (BFOM) of 2.4 GW/cm² was obtained under the conditions of T_p = 500 nm, N_p = 1 × 10¹⁷ cm⁻³, L_p = 5.8 μm and L_m = 0.8 μm. The capacitance–voltage (C–V) characteristics indicated that the PAFP-HFET had a lower C_oss, C_iss and C_rss than the HFET with metal field plates. Above all, the PAFP-HFET shows promise for achieving a high BFOM with conventional III-N fabrication processes.