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 × 10⁸,and ∼5 × 10⁷ 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 × 10¹⁰ to ∼5 × 10⁷ cm^-2 yielded up to a 45-fold decrease in the average reverse Schottky diode current at -10 V bias.