Variable-Sensitivity Photodetector of pn-np Structure for Optical Neural Networks

Abstract
A new structure of the variable-sensitivity photodetector (VSPD) is proposed. It is based on an interdigital pn-np structure. Analog and bipolar photosensitivities varied by the control voltage are described, and the photocurrent is compared with those of the metal-semiconductor-metal (MSM)-type VSPD. Introduction of the pn-np structure is effective for obtaining high photodetection efficiency, and also for modifying the variable-sensitivity characteristics. These advantages make it attractive for optical implementation of neural networks.