Effects Of Electron Irradiation On N-GaN UV Detector

Gallium nitride (GaN) is one of the promising wide bandgap compound semiconductor materials. Ill-nitride compound semiconductor covers the ultraviolet to visible spectral region. Amongst these, it shows unique applications in green, blue or ultraviolet light emitting diodes (LED ), lasers and detectors. Low thermal carrier generation rates and large critical breakdown field make them attractive for the development of electronic devices capable of reliable operation under extreme conditions, such as high power, high temperature and in nuclear environment of the outer space. Recently, several groups have investigated the effect of high energy irradiation on the material properties of GaN. However, there are relatively few reports on the effects of high-energy irradiation on the electrical characteristics of GaN-based device.The electron irradiation damage of GaN Schottky UV detector (Optoway. Inc, 0UVC1-GNA2) has been observed. The structure of the detector has been analyzed using SEM, XPS and AFM. According to the analysis of the structure, GaN Schottky diodes have been made to study the reason of electron irradiation-induced damage.The effects on I-V characteristics observed in the Schottky diodes indicated that even a light-dose irradiation would obviously reduce the reverse breakdown voltage but slightly enlarge the reverse leakage current. The reason that the irradiation induced failure of GaN devices was due to the damage of Au/GaN Schottky interface. This mechanism of the failure may not exist in pn junction type detectors.The effects of irradiation on the UV and visible lights sensitive characteristics ofGaN Schottcky barrier devices also have been investigated using current-voltage (I-V) measurement. After irradiation, the light of UV (380nm) and even visible light, could be detected. The energies of these photons are smaller than the bandgap (3.4eV) of GaN and the lights should not be detected before irradiation. The effects of electron irradiation led to the increasing of visible light background yawp in Schottcky barrier UV detector. This failure mechanism, due to the induced shallow-levels, may be also observed in pn junction photosensitive devices.