In situ characterization of radiation sensors based on GaN LED structure by pulsed capacitance technique and luminescence spectroscopy

We report on variations of the electrical and optical characteristics of commercial GaN blue LEDs, acting as radiation sensors or dosimeters, during 1.6 MeV proton irradiation. Transients of the barrier and storage capacitance have been examined simultaneously with proton-excited luminescence. The pulsed capacitance technique was shown to be a useful tool for the control of changes of the effective density of dopants in the LED structure during proton irradiation, due to introduced radiation defects. The minority carrier injection efficiency can be estimated by measuring the charging current transients of the barrier and storage capacitance. The transient current measurements imply rather fast response of the GaN LED hadron radiation sensors. Also, our results show that the intensity and spectral variations of the proton-excited blue luminescence of the LEDs can be used for the estimation of hadron flux and fluence, respectively. This implies that GaN LED-based sensors can be used for the synchronous detection of hadron irradiation by recording the optical and electrical signals.