Electron Transport Properties in BN Molecular Junction from First-Principles Calculations

Y. Zhaoa, b, Y. Muc, C. Hud, Y. Chengb aLuoyang Institute of Science and Technology, Luoyang 471023, China bCollege of Physics, Sichuan University, Chengdu 610064, China cSchool of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066, China dCollege of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, China

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Density functional theory and non-equilibrium Green's function method are used to study the contact geometry and electron transport properties of BN molecules coupled with Au (100) electrodes. We calculated the conductance of four different coupling morphologies to simulate the stretching and breaking process of the Au-BN-Au molecular junction. The calculated results yield the equilibrium distances of the four configurations as dz=12.631, 9.844, 10.024, 6.424 Å; equilibrium conductances are 0.228G0, 0.975G0, 0.813G0, 5.201G0, indicating that the BN nanojunction has good electron transport properties. A key finding is that within the voltage range from -1.6 to 1.6 V, the current-voltage of nearly all junctions shows a linear relationship, indicating that the BN molecular junction has metal-like properties under low bias voltage. The asymmetry of the I-V curves directly reflects the asymmetry in molecular structure and coupling morphology. These results confirm that the conductance of BN nanojunctions is strongly influenced by the coupling morphology, electrode distance, and external bias voltage of the electrode-connected BN molecules, with the metal-like transport behavior and morphological asymmetry under bias emerging as critical characteristics.

DOI:10.12693/APhysPolA.148.114 topics: BN molecular junction, electron transport, equilibrium conductance, nonequilibrium Green's functions