Study of 14.9 MeV Neutron Irradiation Effects on Ni/GaN Schottky Contacts Using Low-Frequency Noise Spectroscopy

A thorough study of 14.9 MeV neutron irradiation effects on Ni/GaN Schottky contacts is reported. The electrical characteristics and low-frequency noise (LFN) spectra of the irradiated devices are measured and analyzed. The fast neutron irradiation shows an obvious carrier removal effect on the n⁻-GaN with a carrier removal rate of ≈5.5 cm⁻¹, resulting in significantly decreased forward currents of the irradiated devices. The irradiation also increases the inhomogeneity of the Schottky barrier by creating extra trap states at the Ni/GaN interface, according to the temperature–dependent current–voltage (I–V–T) measurements. The LFN analysis reveals an appearance of Lorentzian noise in the irradiated devices, suggesting that one dominant type of trap states located at around 0.52 eV below the conduction band is generated by the 14.9 MeV fast neutron irradiation in the Ni/GaN Schottky contacts.