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Properties of light emitting diodes following cobalt-60 irridiation

Özcan, Şafak
The main purpose of this study is to investigate the effects of gamma radiation on the properties of the light emitting diodes. GaP and GaAsP LEDs are used in the study. It is observed that the exposure of a light emitting diode affects its various properties. A cobalt-60 gamma-cell is used to irradiate the selected light emitting diodes. For the different total doses of gamma pre-irradiation and post-irradiation I-V characteristics and spectral responses are recorded. The capacitance characteristics are measured at 1MHz at room temperature. Gamma ray bombardment of these LEDs results in reduction of electroluminescent intensity and increase in forward current up to levels tested. In GaP diodes dominant current transport mechanism has found to be effected by irradiation. No noticeable change is observed in the series resistances. The impurity density remains same in the green LED and increases in the red one due to the irradiation, which is deduced from the C-V characteristics. Both the circuit designers and the users should be aware of these effects in order to reach a reliable application for these components in a radiation environment.