Neutron irradiation effect on radio-frequency magnetron-sputtered GaN thin films and Au/GaN Schottky diodes

The microstructural and luminescent properties of pre-irradiated and neutron-irradiated sputtered GaN thin films were systematically investigated. Analytical results revealed that the optimal $(1×1013$ $n/cm2)$ neutron irradiation fluence could not only promote the crystallinity of GaN thin films, but also effectively repress the occurrence of deep level luminescence in the photoluminescence spectrum due to the creation of nitrogen-related deep electron traps $(Et1).$ Moreover, from both the Fourier transform infrared spectroscopy and yellow band emission results, it is strongly suggested that Ga–H complexes in the vicinity of the nitrogen vacancy, forming the $Et2$ trap, possibly act as the origin of yellow band emission in GaN material. The superior $I–V$ characteristics resulting from the optimal $(1×1013$ $n/cm2)$ neutron irradiation fluence on the Au/sputtered GaN Schottky diode were attributed mainly to the superior crystallinity, creating the fewer deep electron traps of $Et1,$ leading to a smaller turn-on voltage as well as a larger conduction current in the forward-biased situation. In the reverse-biased condition, the smaller leakage current and the larger breakdown voltage were suggested to probably be due to the presence of fewer nitrogen vacancies and/or less Ga–Au compound formation at the Au/GaN junction.