Design and analysis of normally-off GaN-HEMT using β-Ga2O3 buffer for low-loss power converter applications

An enhancement mode HETM with beta-Ga2O3 buffer is proposed, and its electrical characteristics are analyzed using the physics-based numerical simulator ATLAS TCAD. HEMT with p-GaN/AlGaN/GaN/beta-Ga2O3 utilized for normally-off mode operation of HEMT. The proposed beta-Ga2O3 buffer based HEMT in this work reveals low on-resistance (R-on), high drain current density (I-DS,I- max), high transconductance (g(m,max)), excellent breakdown voltage (VBR) and low gate switching delay. The ultra-wide bandgap beta-Ga2O3 (E-G similar to 4.7 eV) buffer on silicon carbide (SiC) substrate HEMT mitigates the interface-related traps due to nearly lattice match with GaN and suppressing buffer leakage current by serving as a natural back-barrier. This beta-Ga2O3 back-barrier structure increases the 2DEG (two-dimensional electron gas) and mitigates buffer leakage currents. Numerical simulation shows I-DS,I-max of 0.95 A/mm, R-on of 4.26 Omega mm, and V-BR of 835 V. for L-G = 0.8 mu m HEMT. The excellent device characteristics indicate the merits of beta-Ga2O3 buffer-based normally-off HEMT for medium voltage range (<800 V) low resistive loss power converters applications.