Development of Efficient, Radiation-Insensitive Gaas: Zn LEDs

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Abstract
Although amphoterically Si doped GaAs LEDs are commercially popular because of their high light output, they are extremely sensitive to irradiation. Therefore, it would be desirable to have a viable alternative available for radiation environment applications. In this work it is shown that by increasing the hole concentration in the active region of nonamphoterically doped GaAs LEDs, one can simultaneously achieve high light output and law radiation sensitivity. Experimental results indicate that the minority carrier lifetime is smaller in more heavily doped devices so that the lifetime-damage constant, τoK, is also smaller. Hence, the heavily doped devices should have greater radiation hardness. Neutron-induced light output degradation data as a function of hole concentration confirm this conclusion. The results also show that the pre-irradiation light output is greatest in the heavily doped LEDs. The accompanying decrease of τO in the heavily doped devices indicates that the total minority carrier lifetime is at least partially controlled by tne radiative lifetime; a requirement for simultaneously achieving radiation hardness and high initial light output. Finally, an experimental comparison with amphoterically Si doped LEDs shows that the heavily doped devices are superior for neutron fluences greater than 2 × 1012 n/cm2