Armchair α-graphyne nanoribbons as negative differential resistance devices: Induced by nitrogen doping

Using non-equilibrium Green's functions (NEGF) in combination with tight-binding (TB) model, the electronic transport properties of pristine and nitrogen (N) doped armchair a-graphyne nanoribbons (A-alpha-GYNRs) are studied under finite bias. Initially, we have calculated the total energy in order to find the most stable place for N atom. Then we have investigated the effect of width (W) and length (L) of the ribbon and also the position (edge and center of the ribbon) and concentration of doping on the electronic transport properties. Our results reveal that, doping changes the semiconducting behavior of 3n and 3n + 1 A-alpha-GYNRs to semi metallic. Moreover, it is observed that the electronic transport properties are more affected by central doping rather than the edge doping. Interestingly, both edge and central doped ribbons show negative differential resistance (NDR) in all widths. Our results show that doping concentration and the NDR are inversely proportional to each other. We have also found that, as the length of the central region of the device gets longer, the NDR reaches up to 159. Transmission spectrum, bandstructure of the electrodes, Bloch wave functions and density of states (DOS) are analyzed subsequently to more elucidate the electronic transport properties. Our findings could be used to develop the nano-scale NDR devices.