Reduction of Hole Transit Time in GaAs MSM Photodetectors by p-Type &Doping

The temporal responses of the undoped, n-type, and p-type &doped GaAs metal-semiconductor-metal photodetectors were systematically studied. The full-width at half-maximum of the temporal response is significantly improved at low bias for the h-doped detectors compared to the conventional undoped one. The p-type &doped detector exhibits the smallest fall-time, and hence the highest bandwidth, because the induced electric field in the absorption region facilitates the transport of the photo- generated holes. In addition, the p-type &doped detector also gives the highest peak amplitude of the temporal response. Two dimensional simulation on the internal electrical field distribution in the detectors is consistent with the experimental results. HE planar metal-semiconductor-metal photodetectors