High-sensitivity SOI MOS photodetector with self-amplification

A high-sensitivity silicon-on-insulator (SOI) metal-oxide-silicon (MOS) photodetector compatible with conventional silicon technology is proposed. Its operation principle is based on that of a lateral bipolar transistor in spite of an SOI MOS device structure. Photodetectors with narrow base width or short channel length have high current gain which is attributed to a self-biased effect under illumination. Current gain as high as 100 has been achieved for the device with a channel length of 1.0 mu m. Measured intrinsic response time for optical pulses is 19 mu s for the photodetector with a channel length of 0.7 mu m.