CAREER: Exploiting Quantum Optoelectronic Properties of Dirac Quasiparticles in Graphene

University Of Washington, Seattle WA

Investigators

Abstract

**** TECHNICAL ABSTRACT**** This project will investigate and enhance understanding of the quantum electronic and optoelectronic phenomena of graphene - a system with two-dimensional Dirac cone dispersion. Graphene has unique electronic and symmetry properties distinct from other 2D electronic systems, such as the chiral massless dispersion of low energy electrons in single-layer graphene, the tunable effective mass and bandgap in bilayer graphene, and unusual quantum Hall effects with large Landau level spacing at moderate magnetic fields. The integration of ultrafast pump-probe spectroscopy with electrical transport will lead to the investigation of the electronic properties of such systems while benefiting from advanced nano-optical spectroscopy techniques. This proposal comprises investigations of both spatial and temporal dynamics of non-equilibrium excitations with and without magnetic fields, the photovoltaic Hall effect with circularly polarized light, Berry-phase related valley Hall effects, broken-symmetry states, and photocurrent generation in the quantum Hall regime. A fundamental understanding of this technologically important material may lead to new applications including high-speed and low power-consumption electronics, broadband communication, new sensing technologies, and photovoltaics. This multidisciplinary research program provides an excellent platform for undergraduate and graduate students to learn physics, device engineering, and materials science, and for post-doctoral researchers to gain professional experience. ****NON-TECHNICAL ABSTRACT**** As silicon technology faces fundamental limits, breakthroughs in electronics are likely to rely on other materials which allow the exploitation of features and concepts not available in the silicon/oxide system. One promising system is graphene, a single layer of graphite. What sets graphene apart from conventional semiconductors is that the electrons in the graphene behave like photons, traveling with an effective speed just 300 times smaller than the speed of light. This unique feature gives graphene superior physical properties for potential new electronic applications. This project will exploit the novel electronic and optical properties of graphene through a combination of material synthesis, device fabrication, and optoelectronic measurements. In particularly, electron dynamics will be probed by ultrafast laser pulses with a pulse width 13 orders of magnitude smaller than one second. The obtained physical understanding of this technologically important material may lead to high-speed and low power-consumption electronics, broadband communication, new sensing technologies, and photovoltaics. The proposed multidisciplinary research program provides an excellent platform for undergraduate and graduate students to learn physics, device engineering, and materials science, and for post-doctoral researchers to gain professional experience.