Abstract
We simulate the transport and shot noise behavior of graphene armchair ribbons with a series of parallel, unevenly spaced potential barriers with a smooth profile (which could result from the electrostatic effect of negatively biased gates). We analyze the effect of Klein tunneling and resonant tunneling on the individual modes propagating through the graphene channel, showing that this structure can behave as a mode and an energy filter for the charges injected from the contacts. Moreover, we study the different transport regimes (ballistic, strong localized, and diffusive) that can take place inside the graphene ribbon and the effect on the shot noise behavior of the device
Highlights
I N the last few years, a large interest has developed on graphene and related two-dimensional materials [1]–[20]
This has made it possible to observe in graphene, at non-relativistic speeds, relativistic phenomena such as Klein tunneling [35]– [37]
In the case of parallel and spaced barriers, when the structure becomes periodic, the transport behavior is dominated by resonant tunneling through the states quasi-localized in the regions between adjacent barriers, and it has been found that extra Dirac points appear in the graphene spectrum [49]– [54]
Summary
I N the last few years, a large interest has developed on graphene and related two-dimensional materials [1]–[20]. Graphene is a recently isolated and characterized material made up by an planar hexagonal lattice of carbon atoms with sp hybridization. It is transparent and flexible and presents very interesting properties, among which high mechanical strength and electrical and thermal conductivity [21]–[23]. The envelope functions have to satisfy the Dirac-Weyl equation [34], i.e., the same relation which governs the relativistic behavior of massless 1/2-spin particles This has made it possible to observe in graphene, at non-relativistic speeds, relativistic phenomena such as Klein tunneling (a physical phenomenon according to which a relativistic particle orthogonally impinging against a barrier is able to transmit across it with unit probability) [35]– [37]
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