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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:26 |
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Conference: Bucharest University Faculty of Physics 2011 Meeting
Section: Solid State Physics and Materials Science
Title:
Spectrometer for ballistic electrons in graphene in the presence of an applied magnetic field
Authors:
A. Zubarev, Daniela Dragoman
Affiliation:
Univ. Bucharest, Physics Dept.
E-mail
danieladragoman@yahoo.com
Keywords:
graphene, ballistic transport, Landau levels
Abstract:
The propagation of charge carriers in graphene differs from that in other semiconductors because the Schrödinger evolution law is replaced by the Dirac equation. The recent discovery of graphene fabrication methods stimulated the interest in this new material with fascinating electronic, optical and mechanical properties. Despite its large carrier mobility and planar nature, suitable for device fabrication using technologies developed for semiconductor materials, it is difficult to control charge carrier transport in graphene by applying just electric fields. The reason is that graphene has no bandgap and thus the transmission coefficient of charge carriers through gated regions is always unity at normal incidence. Therefore, one can modulate the transmission coefficient either by employing oblique incidence on gated regions or by applying magnetic fields. When a sufficiently strong magnetic field is applied on a graphene sheet, the available energy levels of charge carriers become discrete, so that electron filtering can be achieved in a similar way as by a resonant tunneling diode. We have studied in detail the ballistic charge carrier propagation in graphene in the presence of magnetic fields applied on stripes and have found that it is possible to select charge carriers with certain energy by applying both electric and magnetic fields. We use the fact that the transmission coefficient of charge carriers depends on the angle of incidence, so that when this angle is fixed by an applied electric field, it is possible to select only the charge carriers on a certain landau level. In this way, electrodes positioned at several angles collect charge carriers with certain energies, in a similar way as a spectrometer filters specific wavelengths of the input radiation by controlling the position of its output aperture.
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