Electrical Characteristics of Mid-wavelength HgCdTe Photovoltaic Detectors Exposed to Gamma Irradiation

Abstract

The study of electrical characteristics of mid-wavelength HgCdTe photodiodes irradiated by steady-state gamma rays has been carried out. The measurement of the current-voltage curves during irradiation revealed an abnormal variation of zero biased resistance R 0 , and it didn't tend to change monotonically as observed in the case of post irradiation measurement. The irradiation effect was dominated by bulk effect inferred from the fitting calculations, and the generation-recombination current in the depletion region was drastically affected by gamma irradiation. Another irradiation effect was the linear increase of the series resistance with irradiation dosage which was related with the change of transportation parameters of carriers. The influence of hydrogenation on the gamma irradiation effects was also studied for comparison with the same batch of HgCdTe photodiodes, and it was found that R 0 for the hydrogenated devices showed similar change to those without hydrogenation. The series resistance, however, gave a totally different irradiation effect from the non-hydrogenated detectors and showed little change up to nearly 1 Mrad(Si) of gamma irradiation, which may be explained by the annihilation of hydrogen radicals with the defects caused by gamma irradiation.

Total ionizing dose effects on HgCdTe infrared focal plane arrays

“…The dark current decreases significantly when the total dose reaches to 20krad, and further decreases when the total dose reaches to 80krad. According to the experimental results, it is known that the HgCdTe photodiode is not sensitive to the TID and the dark current of the device does not change significantly after irradiation 11 . 12 Therefore, it can be inferred that the decrease of dark current of the IRFPA after irradiation is not due to the decrease of current in the HgCdTe photodiode part.…”