Effects of electron-irradiation on electrical properties of AlGaN/GaN Schottky barrier diodes

Abstract

Effects of 1 MeV electron-irradiation at room temperature on the electrical properties of AlGaN/GaN heterostructures, including leakage currents, threshold voltages, and electron traps, have been investigated using Schottky barrier diodes (SBDs) fabricated on the AlGaN. The SBDs, before and after the irradiation with a dose of 5×1015 cm−2, were characterized by temperature dependent current-voltage and capacitance-voltage measurements and deep level transient spectroscopy. It is found that the irradiation causes (i) significant increase in leakage currents, dominated by tunneling conduction, at both reverse and low-forward biases; (ii) a clear negative shift in threshold voltage in the pinch-off region; and (iii) creation of traps Ae(∼1.1 eV) or A2(1.2 eV) and Ee(0.09 eV) in the GaN buffer and AlGaN regions. The irradiation-induced traps can be used to account for the increase in leakage currents and shift in threshold voltage. However, as compared to traps A2(1.2 eV) and E(0.13 eV) induced in thick GaN layers by electron-irradiation, the irradiation-induced traps in the AlGaN/GaN heterostructures show some changes in activation energy and electron capture behavior.