Electrically-induced n-i-p junctions in multiple graphene layer structures

The Fermi energies of electrons and holes and their densities in different graphene layers (GLs) in the n- and p-regions of the electrically induced n-i-p junctions formed in multiple-GL structures are calculated both numerically and using a simplified analytical model. The reverse current associated with the injection of minority carriers through the n- and p-regions in the electrically-induced n-i-p junctions under the reverse bias is calculated as well. It is shown that in the electrically-induced n-i-p junctions with moderate numbers of GLs the reverse current can be substantially suppressed. Hence, multiple-GL structures with such n-i-p junctions can be used in different electron and optoelectron devices.Comment: 7 pages, 6 figure

Plasmonic shock waves and solitons in a nanoring

We apply the hydrodynamic theory of electron liquid to demonstrate that a circularly polarized radiation induces the diamagnetic, helicity-sensitive dc current in a ballistic nanoring. This current is dramatically enhanced in the vicinity of plasmonic resonances. The resulting magnetic moment of the nanoring represents a giant increase of the inverse Faraday effect. With increasing radiation intensity, linear plasmonic excitations evolve into the strongly non-linear plasma shock waves. These excitations produce a series of the well resolved peaks at the THz frequencies. We demonstrate that the plasmonic wave dispersion transforms the shock waves into solitons. The predicted effects should enable multiple applications in a wide frequency range (from the microwave to terahertz band) using optically controlled ultra low loss electric, photonic and magnetic devices.Comment: 13 pages, 12 figure

Gas Sensing with h-BN Capped MoS2 Heterostructure Thin Film Transistors

We have demonstrated selective gas sensing with molybdenum disulfide (MoS2) thin films transistors capped with a thin layer of hexagonal boron nitride (h-BN). The resistance change was used as a sensing parameter to detect chemical vapors such as ethanol, acetonitrile, toluene, chloroform and methanol. It was found that h-BN dielectric passivation layer does not prevent gas detection via changes in the source-drain current in the active MoS2 thin film channel. The use of h-BN cap layers (thickness H=10 nm) in the design of MoS2 thin film gas sensors improves device stability and prevents device degradation due to environmental and chemical exposure. The obtained results are important for applications of van der Waals materials in chemical and biological sensing.Comment: 3 pages; 4 figure