Negative differential resistance in parallel single-walled carbon nanotube contacts

Based on first-principles calculations, we investigate the electron transport properties of parallel single-walled carbon nanotube contact. A significant negative differential resistance (NDR) behavior is found due to staggered electron gratings in energy space and standing waves in real space on the two tubes induced by bias. Such a NDR effect is robust against the contact length, the tube diameter, the shape of the end, and the difference in the two electrodes. Because no bridging molecule is used, the structure of this NDR device is simpler compared with ordinary molecular NDR devices. Our findings are expected to promote the discovery of more NDR devices composed of only two electrodes in parallel contact.