Reduction of buffer leakage in AIGaN/GaN HEMTs with an AIGaN current-blocking barrier by using a two-dimensional simulation

We report improved transport characteristics for of AIGaN/GaN/AIGaN double heterostructure (DH) high-electron-mobility transistors (HEMTs) with an AIGaN current-blocking-barrier (CBB) structure. The proposed device features a 40-nm-thick AIGaN CBB embedded into a conventional AIGaN/GaN HEMT to prevent the two-dimensional electron gas (2-DEG) of the HEMT from spilling over the buffer layer, effectively reducing the buffer leakage current. Simulation results clearly indicate that the proposed AlGaN/GaN/AlGaN DH-HEMT has not only better current confinement of the 2-DEG channel but also less leakage currents into the GaN buffer layer compared with the conventional AIGaN/GaN HEMT. In the DH-HEMT with an AIGaN CBB, we observed an approximately 56.9 % improvement in the maximum drain current density (ID,max) and a 16 % improvement in maximum transconductance (gm,max) at zero gate bias condition over the conventional SH-HEMT.