Electronic transport properties of carbon and boron nitride chain heterojunctions

Long, stable, and free-standing linear atomic carbon chains and boron nitride (BN) chains have been carved out from their 2D sheets recently [Meyer et al., Nature, 2008, 454(7202), 319; Jin et al., Phys. Rev. Lett., 2009, 102(20), 205501; Cretu et al., ACS Nano, 2014, 8(12), 11950], which could be used as transport channels or on-chip interconnects for field-effect transistors. Herein, the transport properties of carbon and BN chains and their heterojunctions are investigated using the nonequilibrium Green's functions in combination with density functional theory. All the atomic chains exhibit even-odd behavior and the transport property is limited for longer lengths. The current rectifying effect is observed in the even-numbered configurations except pure carbon chains, which originates from the atomic structure induced by the asymmetric electronic structure. Moreover, the transmission probability of the double chain channel is enhanced two times. Importantly, the DOS of the chain channel dominates the transmission spectrum and current-voltage characteristics of devices. For the carbon and boron nitride chain heterojunctions, their electronic properties could be modulated by changing the position and number of carbon or boron nitride atoms. Particularly, the structures with carbon atoms at the junction show better electron transport properties, where the current and rectification ratio are enhanced evidently. When spin polarization is considered, they are magnetic semiconductor and show an evenodd spin filtering effect. Moreover, the spin filtering effect is enhanced in the cases with carbon chains on one side. This study may provide a new pathway for the exploration of nano-electronics.