Induced rectification behavior in armchair SiC nanoribbon by Al and P doping

Abstract

The rectification behavior of the armchair SiC nanoribbons devices with the substitutional aluminum (Al) and phosphorus (P) impurities are investigated using density functional theory (DFT) and non-equilibrium Green’s function (NEGF) frameworks. The band structures of electrodes, molecular energy spectrum, transmission spectrum and projected device density of states are considered to analyze the results. The devices include two armchair SiC nanoribbons with the 7 and 9 atoms widths (named 7ASiCNR and 9ASiCNR, respectively) and the impurities in the center or edge of the electrodes. From the results, we found that the impurities change the electrical behavior and induce rectification of the devices whether the position of the impurities is in the center or edge of the electrodes. Among these devices, the highest rectification ratio has occurred for the 7ASiCNR device with simultaneous Al and P impurities located in the center of electrodes with the value of 2.29 × 1013. Moreover, in this device, the forward bias threshold voltage is near to zero. From the band structure analysis, it is found that by doping of Al (P) atoms in the ASiCNRs, the bands shift upward (downward) so that the electrode became a p-type (n-type) semiconductor. Therefore, the bands became well-matched and the high density of states in the central region is provided. This cause the electrons can be allowed to transport.For both Al and P atoms impurities, the rectification is obtained but the rectification ratio in the case of simultaneous Al and P impurities is more than Al or P doping due to the better matching of energy bands. For example, in the 7ASiCNR devices, the rectification ratio increases from 1.65 × 104 (P-doped) to 2.29 × 1013 (P- and Al-doped).