An ab initio study on the transport characteristics of Si2C2 clusters

摘要

We have studied the transport properties of three different contact structures in Si2C2 clusters by using the first principles based on density functional theory (DFT) and non-equilibrium Green's function (NEGF) in this paper. Both M1 and M2 show excellent transport properties and a weak negative differential resistance (NDR) phenomenon appears due to greater transferring charge between the central area and the electrodes. The intermediate barrier of M3 is very large, and the electrons are difficult to transmit. However, it also shows good conductivity after we add sulfur (S) atoms at both ends of the molecule. Through the molecular projected self-consistent Hamiltonian (MPSH) analysis, the molecular orbital is expanded with the addition of S atoms, thus showing good conductivity. With the addition of the bias, the conductance of Si2C2 clusters at the Fermi level is reduced due to the drift of the energy level. It is interesting to note that there is a high resonant transmission peak at -1.14 eV under 2 V bias of the M3 system, which shows a molecular switching behavior.