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Seminário Extra de Matéria Condensada

Dia: TERÇA-FEIRA, 22/07/2014
Horário: 11h
Local: sala de reuniões (antiga biblioteca, 1P)

Título: New alternatives to improve biomolecules sensing using a 2D nanodevices.

Apresentador: Rodrigo Garcia Amorim (Department of Physics and Astronomy
Uppsala University)

Abstract:

One of the challenges for the next generation of DNA sequencing is to have a robust, stable
and feasible nanodevice. In this work we will show two different proposals along this
direction. First, we will present one alternative as a device, hexagonal silicon 2D material,
silicene. This material was recently discovered and has similar electronic structure
compared to graphene but differs in its geometry
(buckled structure) and the bonding (a combination
of sp2-sp3 hybridization). In that case, as we can see
in the top Figure, the nucleobases are adsorbed on
the 2D material and it is extremely important to describe the interaction between the device
(silicene) with the nucleobases (A, C, G and T). The standard DFT with GGA exchange
correlation potential approximation is not capable to describe the long range interaction
and take into account this type of interaction. We
will show results for nucleobases on top of silicene
employing an approximation with van der Waals
correction and the transport calculation including
this new computational ingredient. Intriguingly,
despite the weak interaction between nucleobases
and silicene, considerable changes in the
transmittance at zero bias are predicted by us.
Secondly, we will show how to improve the sensing of a graphene nanodevice to detect a
single nucleobase. For this purpose we will use graphene with a nanogap with border
functionalization (hydrogen or nitrogen). We used density functional theory (DFT) combined
with the non-equilibrium Green's function (NEGF) method to study individual nucleobases in
the graphene gap. We will show how to identify nucleobases with such a graphene nanogap
devices (bottom Figure) and how we can improve the sensing of these devices.