Shape effects in graphene nanoribbon resonant tunneling diodes: A computational study

The possibility of using graphene nanoribbons (GNRs) as the material for resonant tunneling diodes (RTDs) was investigated using a device simulator based on the nonequilibrium Green's function with the pi-orbital tight-binding approach. The double-barrier quantum well (DBQW) requirements of a RTD can be implemented by adjusting the width of a GNR to derive a negative differential resistance (NDR). The implementation of such a device is demonstrated in this paper and its mechanism was also found to be robust regardless of the eventual shape of the GNR patterned. Furthermore, the effects of the shape of the patterned GNR and the operating temperature on the performance of the device were explored by looking at the real space current flux of the device and the temperature dependency of the peak-valley ratio (PVR), respectively. Although the different shapes of GNR RTDs had a similar DBQW structure, their PVRs were different due to their conduction mechanisms which were dependent on the different geometrical shapes of each case. Lastly, the effect of thermal broadening, and width/length dependence of the central GNR between two barriers on the device performance, was further investigated in order to provide insights into the device physics of GNR RTDs for future study on performance optimization.