Radiation response of optically-triggered GaAs thyristors

Gallium arsenide optically triggered thyristors that exhibit tolerance to high X-ray dose rates have been fabricated. These two-terminal epitaxial devices feature breakover voltages of 18 V to 38 V with no radiation. They trigger at less than 2 V with only tenths of a milliwatt of laser light, but they do not trigger at 2×10⁹ rad(Si)/s with a bias level as much as 40% to 60% of the zero-radiation breakover voltage. When these devices are bombarded with neutrons, the reduced carrier lifetimes result in a decreased sensitivity to triggering by light and ionizing radiation. The thyristors show some decrease in optical and X-ray sensitivity upon neutron exposure in excess of 10¹³ n/cm². At 10 ¹⁴ n/cm², there are major reductions in photon sensitivity, and some instability is observed