Photodiode with Low Dark Current Built in Silicon-on-Insulator by Electrostatic Doping

In this work, we demonstrate experimentally a novel photodiode built in the silicon-on-insulator (SOI) substrate. Compared to conventional photodiode, where the p-n junction is formed by diffusion or ion implantation, the p-n junction in our work is formed by electrostatic doping induced by top and bottom gates. The fabricated device used for photodetection at λ = 520 nm, shows a dark current 3 decades lower than a conventional photodiode. Furthermore, the device can be switched between photodiode mode with low reverse current and resistor mode with much higher current. This unique property can be exploited in the operation of a photodetector array.