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

Abstract

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 d_z = 12.631, 9.844, 10.024, 6.424 Å;  equilibrium  conductances  are  0.228 G₀, 0.975 G₀, 0.813 G₀, 5.201 G₀, 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.