Effects of Threading Dislocation Density on the Gate Leakage of AlGaN/GaN Heterostructures for High Electron Mobility Transistors

AlGaN/GaN heterostructures were regrown on three semi-insulating GaN templates with threading dislocation densities of ∼2 × 10 10 , ∼5 × 10 8 , and ∼5 × 10 7 cm -2 . Regrowths were carried out under Ga-rich conditions by plasma-assisted molecular beam epitaxy to determine the effects of threading dislocation density on leakage through Schottky contacts on the AlGaN/GaN heterostructures. A similar AlGaN/GaN heterostructure was directly grown on 4H-SiC under Ga-rich conditions for comparison with the regrown heterostructures. High electron mobility transistors were fabricated. Decreasing the threading dislocation density from ∼2 × 10 10 to ∼5 × 10 7 cm -2 yielded up to a 45-fold decrease in the average reverse Schottky diode current at -10 V bias.