Transient Effects of Ionizing Radiation in Photodiodes

We report here on photodiode structures designed and fabricated to reduce the amplitude of unwanted, noise current induced during exposure to ionizing-radiation environments, without significantly reducing the desired photodiode signal current. For the optical wavelength range from .7 ¿m to 1.4 ¿m, we have studied three types of photodiode structures fabricated from AlGaAs, AlGaSb, and InGaAsP compound semiconductor materials. We also have tested and compared these specially fabricated, radiation insensitive photodiodes with commercially available photodiodes in an ionizing-radiation environment.