A PMOS tunneling photodetector

A metal/oxide/n-Si structure with ultrathin gate oxide is utilized as a photodetector. At inversion gate bias, the dark current and photocurrent are determined by both the minority carrier (hole) generation rate in the deep depletion region and the electrons tunneling from the gate electrode to n-type Si, while only the former component is significant in the NMOS photodetector. The electron tunneling current dominates the photocurrent at sufficiently large negative gate voltage, and the sensitivity of PMOS detectors is, therefore, enhanced by approximately one order of magnitude, as compared to NMOS detectors.