University of Virginia, USA
Title: Inspired by photonics - unconventional electron flow across 2-D P-N junctions
Biography: Avik Ghosh
With the current slow-down of Moore's law and the abolition of the ITRS roadmap, there is a pressing need to explore various materials, architectural and physical solutions for low-power electronics, ranging from spintronics to 2D materials to subthermal switching that beats the fundamental Boltzmann limit. Graphene and other 2D materials have been widely studied because of their photon-like band structure and high mobility. However, their gaplessness compromises their ability to switch under gate bias. I will discuss how using a sequence of gated PN junctions, we can make electron flow in graphene resemble optics-with unconventional equivalents of Snell's law for trajectories, Fresnel equation for transmission, Malus' law for polarization and cut-off modes of a waveguide. These equivalents (negative index, Klein tunneling and Veselago focusing) can be used to filter electrons and engineer a gate-tunable transport gap that allows us to turn off the electron flow abruptly without hurting the mobility of the on current. This novel switching has implications for both digital devices and high speed analog RF applications. Extended to 3D topological insulators, the unconventional switching allows us to filter the spins, amplifying their torque at an injecting ferromagnetic by giving us a gate-tunable giant spin hall angle.