Removing long tails from photoconductive detectors: A new minority hole sinked photodetector

Transit-time limited photoconductive detectors generally have a long tail ranging from several hundred picoseconds to several nanoseconds in the fall time of an impulse response. We have developed a new photoconductive detector called minority hole sinked photodetector to remove this long tail. This detector incorporates a p-type back gate to drain out the slow-moving minority holes. Improvement of the fall time from 1 ns - 450 ns down to 80 ps has been achieved with a reverse gate bias of V. This back-gate biasing causes no effect on the responsivity of the detector under high speed operation. Furthermore, the back-gate bias can reduce the noise power (in a 50ω load) by 1 dB at 100 MHz and 0.25 dB at 800 MHz at 1.2 MHz noise bandwidth. We believe that this detector should be useful for gigabit-rate lightwave communication as well as for integrated photoreceiver applications.