Abstract
We theoretically demonstrate a Dirac fermion metagrating which is an artificially engineered material in graphene. Although its physics mechanism is different from that of optical metagrating, both of them can deliver waves to one desired diffraction order. Here we design the metagrating as a linear array of bias-tunable quantum dots to engineer electron beams to travel along the -1st-order transmission direction with unity efficiency. Equivalently, electron waves are deflected by an arbitrary large-angle ranging from 90° to 180° by controlling the bias. The propagation direction changes abruptly without the necessity of a large transition distance. This effect is irrelevant to complete band gaps and thus the advantages of graphene with high mobility are not destroyed. This can be attributed to the whispering-gallery modes, which evolve with the angle of incidence to completely suppress the other diffraction orders supported by the metagrating and produce unity-efficiency beam deflection by enhancing the -1st transmitted diffraction order. The concept of Dirac fermion metagratings opens up a new paradigm in electron beam steering and could be applied to achieve two-dimensional electronic holography.
Highlights
Graphene has emerged as a promising platform for developing alternative electronic devices with higher performance and even microelectronics because of its exceptional properties such as high intrinsic mobility, high electrical conductivity, and ballistic transport at micron scales under ambient temperatures[1]
In this paper a Dirac fermion metagrating is illustrated with the extraordinary wave beam manipulation abilities, theoretically realized by a linear array of gate-bias-controlled quantum dots (QDs)
Perfect large-angle beam deflection the bending of Gaussian beams at three different angles θWA, QDs are circular potential steps that can be tuned by applying a simulated by using nanoscale QDs
Summary
Graphene has emerged as a promising platform for developing alternative electronic devices with higher performance and even microelectronics because of its exceptional properties such as high intrinsic mobility, high electrical conductivity, and ballistic transport at micron scales under ambient temperatures[1]. One has to take on the risk of loss of high intrinsic mobility of electrons, which is an advantage of graphene over conventional semiconductor materials Another option demonstrated experimentally is to manipulate electron waves at the neutrality point where the conductivity drops with a power-law temperature dependence[36]. In addition to the limited deflection angle, a smooth and sufficiently long transition region is required in such a waveguide to ensure high transmission through the bends, which prevents downsizing of electron units. In contrast to these approaches, the metagrating steers electron beams without the requirement of opening a complete bandgap or extremely low temperatures and simultaneously caters to the desire for miniaturization. By controlling the QD bias V, negative transmission with unity efficiency can be achieved
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
