Development of a new photodetector based on two dimensional hole gas

We have previously demonstrated the improved time response performance of the heterostructure metal-semiconductor-metal (HMSM) photodetector, due to the presence of a two-dimensional electron gas (2DEG). However, the time response presents a long tail due to the slow moving holes, which would still be an impediment for high frequency operation. In order to overcome this limitation, we have developed a new photodetector based on a two-dimensional hole gas (2DHG) in which the electric field in the GaAs absorption layer attracts the photogenerated holes to a reservoir of holes thus reducing their transit time. We present the designed structure, fabrication sequence, current-voltage, capacitance- voltage characterizations carried out in the dark and under light. Time response data verifies a distinctive reduction in tail of response as expected.