Development of a new photodetector based on two dimensional hole gas

We have previously demonstrated the improved performance in terms of high-speed properties of the heterostructure metal-semiconductor-metal (HMSM) photodetector, given by the presence of the two-dimensional electron gas (2-DEG) at the AlGaAs/GaAs heterojunction. However, the time response presents a long tail due to the holes, which would still be an impediment for high frequency operation. In order to overcome this limitation, we are developing a new photodetector based on a two-dimensional hole gas (2-DHG), in which the electric field in the GaAs absorption layer would attract the photogenerated holes. We present here the designed structure, the fabrication sequence and current and voltage characterizations carried out in the dark and under light excitation on devices with two different p-type delta doping.