High temperature and trap sates characterization of Al0.35Ga0.65N/GaN/Al0.25Ga0.75N double heterojunction

In this work, the high temperature and trap sates characteristics have been investigated for Al0.35Ga0.65N/GaN/Al0.25Ga0.75N double heterojunction. By using high-Al AlGaN barrier and back barrier layers, the maximum current at 200 ℃ is reduced by 35%, which is much lower than 58% reduction for conventional double heterojunction. The ION/IOFF ratio is as high as 4.6 × 107 at 200 ℃, demonstrating the excellent high-temperature characteristics of high-Al AlGaN barrier layer. For Al0.35Ga0.65N/GaN/Al0.25Ga0.75N double heterojunction, the shallow trap state density DT of 3.57 × 1011–1.37 × 1013 cm−2eV−1 is located at energy ET in the range of 0.259–0.322 eV, and the deep DT of 0.237–2.19 × 1013 cm−2eV−1 is located at energy ET in the range of 0.388–0.441 eV. The trap densities for heterojunction with high-Al AlGaN barrier and back barrier are lower than those for heterojunction with low-Al AlGaN back barrier.