Abstract:
Advances in silicon-based digital electronics and improved understanding of the human brain have spurred tremendous interest in artificial intelligence and neuromorphic computing. Last few decades saw a rapid rise in both computation power and theoretical framework that resulted in a more efficient solution for specialized cognitive tasks. Since logic processing and memory are intimately connected, the neural computation is not burdened by von Neumann bottleneck. However, progress in artificial intelligence has fallen short of initial predictions and inspired the new approach of hardware implementation using a nano-ionic device that mimics biological neuron at a fundamental level.
I will discuss an artificial synapse realized in a device called memtransistor that is based on a single layer semiconducting MoS2. The internal resistance of the device is tuned not only by the biasing history but also by a third gate terminal. Furthermore, open architecture channel allows multiple electrodes resulting in elusive heterosynaptic plasticity -a necessary ingredient for hyper-connectivity. In addition, an artificial neuron is needed to integrate signals received via synapses and fires a charge wave along axon causing subsequent synaptic switching. Thus, I will discuss a practical route to design artificial neurons based on films from solution-processed two-dimensional materials that embody two coupled state variables (temperature and charge) needed for action-potential based computation. An alternative artificial neuron based on heterojunctions will also be presented to circumvent the issues of stochasticity. Finally, a new fabrication method and a new memtransistor crossbar architecture will be discussed to achieve the desired scaling. I will conclude with future goals in fundamental research and applications.
Bio:
Dr. Vinod K. Sangwan is currently a postdoctoral researcher with Prof. Mark C. Hersam in the Department of Materials Science and Engineering at Northwestern University. He did a B. Tech. in Engineering Physics at Indian Institute of Technology Mumbai and later, a Ph.D. in Physics with Profs. Ellen D. Williams and Michael S. Fuhrer at the University of Maryland College Park. His research at Northwestern spans across several disciplines including applied physics, electrical engineering, materials science, and chemistry. His current interests are defects dynamics in the 2D materials, nanoscale transport, ultrafast optical processes, emerging photovoltaic materials and devices, and quantum materials.