جستجوی مقالات مرتبط با کلیدواژه « Quantum transport » در نشریات گروه « شیمی »

We have investigated structure and electronic properties of Au and Si liner chains using the firstprinciplesplane wave pseudopotential method. The transport properties and conductance of these twoliner chains are studied using Landauer approaches based on density functional theory (DFT). Weobtain density of states and band gap using Kohn-Sham and Wannier functions as well as quantumconductivity and current for Au and Si liner chains. We study the effect of Hubbard U on quantumconductivity and current for Au liner chain within DFT+U for strongly correlated systems. Wecompare the source of the states around Fermi level of these systems that have important role inconductivity. We present I-V characteristics of the Si and Au liner chain. Results show Ohmicbehavior of current flow in the liner chains in terms of applied bias voltage. We show that Hubbard Ucorrection removes the unphysical contribution of d electrons to the conductance of Au liner chain,resulting in a single transmission channel and a more realistic conductance of 1G0 that is in goodagreement with experimental results. Our calculations reveal that monatomic chains of Si and Au aremetallic therefore they can be used as connectors between nanoelectronic devices.

The quantum transport computations have been carried on four different width of zigzag graphene using a nonequilibrium Green’s function method combined with density functional theory. The computed properties are included transmittance spectrum, electrical current and quantum conductance at the 0.3V as bias voltage. The considered systems were composed from one-layer graphene sheets differing with each other in y-direction width. The number of unit cells for considered graphenes are one, three, five and seven in z-direction, whiles the scattering region and first super cells of semi-infinite right and left electrodes were formed from three unit cell in z-direction. At the first the considered structures have been optimized and next the NEGF calculations were carried out on the optimized structures. All of the computations have been done using OPENMX3.6 atomic scale simulation code. The results were presented and interpreted for the considered systems in terms of the z-direction width of studied graphenes.

A comprehensive study of Schottky barrier MOSFET (SBMOSFET) scaling issue is performed to determine the role of wafer orientation and structural parameters on the performance of this device within Non-equilibrium Green's Function formalism. Quantum confinement increases the effective Schottky barrier height (SBH). (100) orientation provides lower effective Schottky barrier height in comparison with (110) and (111) wafers. As the channel length of ultra thin body SBMOSFET scales down to nanoscale regime, especially for high effective SBHs, quantum confinement is created along the channel and current propagates through discrete resonance states. We have studied the possibility of resonant tunneling in SBMOSFET. Resonant tunneling for (110) and (111) orientations appear at higher gate voltages.