Pablo Jarillo-Herrero’s investigation of the basic properties of an amazing new material called graphene may help fulfill its touted role in revolutionizing electronics and other industries.
Jarillo-Herrero, Mitsui Career Development Assistant Professor of Physics, studies how electrons are influenced by quantum mechanical principles as they are transported through low-dimensional nanomaterials such as graphene, topological insulators, and carbon nanotubes. Among these, graphene, the single-atom thick, two-dimensional version of the form of carbon called graphite, became the best-known since the 2010 Nobel Prize was awarded to two UK physicists for groundbreaking experiments that shed initial light on graphene’s extraordinary electrical properties.
Jarillo-Herrero is looking at how and why this exceptionally thin, strong material conducts electricity better than any material known to man. Graphene’s unique properties, which allow electrons to propagate through it for long distances without bouncing off obstacles, may make it a serious candidate to replace silicon and other conventional semiconductors in a variety of nanoelectronic applications. In addition, graphene’s optoelectronic properties could make it useful in a new generation of solar cells, ultra-high speed photodetectors, and other energy-harvesting devices.
“We fabricate graphene nanodevices and measure quantum electronic transport within them,” Jarillo-Herrero said. “We send a current through the devices to observe how electrons propagate through the material and how they react to obstacles in their path, as well as how light and electrons interact within it.” He subjects the material to the ultra low temperatures and the very high magnetic fields in which its most interesting quantum properties become apparent.
Oddly, electrons propagate through graphene more like photons, which have no mass, than typical electrons, which do. Electrons do not move through graphene at the speed of light but they move with a velocity that is independent of their energy. “This doesn’t happen in normal materials,” Jarillo-Herrero said. Another key feature is that electrons moving through graphene can go through any obstacle without being reflected, while electrons moving through other materials are scattered when they encounter impurities. This phenomenon, never measured before, is ultimately responsible for the exceptional “bounce-free” propagation of electrons through graphene.
“Graphene’s properties are so unusual that they may lead to totally unexpected applications, such as a new generation of computation and processing, cheaper display screens in mobile devices, flexible displays, storing hydrogen for fuel cell powered cars, sensors to diagnose disease, and high-performance batteries. Ultimately, far down the road, my research could be used in those applications,” Jarillo-Herrero said. In the meantime, knowledge gleaned from his experiments will help fuel the imaginations of the many MIT researchers and others who envision new real-world devices and applications based on graphene and other materials spawned by basic science.