Low dark current photosensors based on GaAs0.6P0.4

Photosensors based on n-type GaAsP have been investigated in two types of structures: MOS layers with anodic insulators, and Be-implanted diodes. The MOS sensors show low dark current, long storage times, and response to nearly the entire visible spectrum. These sensors have storage times exceeding 500 seconds and are limited by oxide leakage current. Optically generated holes are collected under the gate and read out by a charge injection technique. Applications to sample and hold detection are discussed. The photodiodes, formed by implanting Be in n-type GaAsP, have high sensitivity, large dynamic range, and a 50 nanosecond rise time at zero bias. They are potentially useful as low light level high speed photodetectors.