Gamma radiation effects on light emitting and variable capacitance devices

Abstract EN

Gamma radiation doses as low as a few krads caused significant increases in the output of light-emitting diodes (LEDs).

Further irradiation, above 10 krad, produced permanent radiation damage associated with the degradation of light emitted and the output electrical characteristics.

Capacitance-voltage and current-voltage measurements have shown that LED devices are sensitive to the gamma-ray dose.

Such behavior suggests that LED devices can be successfully employed for the determination of absorbed dose in the relatively low gamma dose range.

Following irradiation, shelf annealing of the damaged cells, at room temperature for 200 days, leads to recovery of 17-18% of their initial output light intensity.

Oven annealing at different temperatures ranging up to 500°C, for 50 minutes, shows that the output light intensity levels recover to around 22%, 25%, 33%, 43%, and 67.5% of the initial values under the influence of annealing temperature levels of 100°C, 200°C, 300°C, 400°C, and 500°C respectively.

Varactor type "BA102" offered a high resistance to gamma exposure.

The response of its (C-V) and (I-V) relationships to radiation started only in the Mrad range, where the change is found to occur over a relatively wide radiation dose range (up to 130 Mrads).

The ratio of capacitance variation (CIC0) due to gamma irradiation is increased from 2.7, at zero dose, to 4.5 after exposure to 50 Mrads and at a reverse bias of 10 volts.