Variable-sensitivity photodetector that uses a metal-semiconductor-metal structure for optical neural networks

A novel type of photodetector called a variable-sensitivity photodetector has been developed for optical implementation of neural networks. It utilizes a metal-semiconductor-metal structure whose quantum efficiency can be modulated by an applied bias voltage. A linear dependence of the sensitivity on the bias voltage was obtained with the bipolar current flow. This device operated as a multiplier of the incident light intensity and the bias voltage. It is shown that this device is suitable for achieving dynamic synaptic interconnections. A 4 x 4 array device was fabricated and demonstrated.