CVD grown bilayer MoS 2 based artificial optoelectronic synapses for arithmetic computing and image recognition applications

Abstract Demand for lower computing power has rapidly increased. In this context, brain-inspired neuromorphic computing, which integrates data storage and processing, has attracted significant attention. Here, our study reveals that field effect transistors fabricated on chemical vapor deposited bilayer (2L) MoS 2 films can mimic the functions of biological synapse. These devices demonstrate high levels of pair pulse facilitation, short term to long term memory (STM-to-LTM) transition as well as learning-forgetting-relearning properties. The effects of light intensity, pulse number, pulse width and photon energy on the STM-to-LTM transition are studied. It has been found that the rate of depression of the memory state can be controlled using the gate bias. Electrical and optical energy consumptions per synaptic event are estimated to be as low as 280 fJ and 20 nJ, respectively. Furthermore, the photocurrent in these devices is observed to increase linearly with the number of excitation pulses. This property has been exploited to demonstrate different arithmetic operations using the device. Moreover, these devices show great potential for image recognition. Artificial neural network simulation has returned an image recognition accuracy of ∼85%. All of these findings show a great prospect of 2L-MoS 2 for developing low power, transparent and flexible neuromorphic devices.