Reduction of Buffer Leakage in AlGaN/GaN HEMTs with an AlGaN Current-Blocking Barrier by using a Two-Dimensional Simulation

Abstract

We report improved transport characteristics for of AlGaN/GaN/AlGaN double heterostructure (DH) high-electron-mobility transistors (HEMTs) with an AlGaN current-blocking-barrier (CBB) structure. The proposed device features a 40-nm-thick AlGaN CBB embedded into a conventional AlGaN/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 AlGaN/GaN HEMT. In the DH-HEMT with an AlGaN CBB, we observed an approximately 56.9 % improvement in the maximum drain current density (I-D,I- max) and a 16 % improvement in maximum transconductance (g(m, max)) at zero gate bias condition over the conventional SH-HEMT.