Application of Damage Constants in Gamma Irradiated Amphoterically Si-Doped GaAs Leds.

The effect of gamma irradiation on the electrical and optical properties of amphoterically Si-doped GaAs LEDs has been investigated. The lifetime-damage constant product for degradation of the light output at constant low voltage was found to be 7.5 X 10 to the minus 7th powerrads. However, because of the presence of space charge limited current SCLC flow at higher currents, which conform to the practical operating range of 10 to 50 microamps, the light output degraded more rapidly than at lower voltages. It is shown that the same value of the lifetime damage constant product can be used to predict the degradation at practical operating currents when the SCLC is taken into account. Consequently, the practical implications of the results are that care must be taken in predicting degradation with a low voltage lifetime damage constant product, and that the doping conditions leading to the presence of the SCLC should be avoided for LEDs that must operate in a radiation environment. Author