Electron transport properties of Si-based nanowires with substitutional impurities

The electron transport properties of ultrathin Si nanowires with various substitutional atoms located at different positions are theoretically studied by using the nonequilibrium Green function combined with the extended Huckel theory. The results show that there exists a close correlation between the symmetry of the current-voltage curves and the position of substitutional atoms of these nanowires. Various patterns of negative differential resistance (NDR) appear, which are also related to the substitutional position in the nanowires. Moreover, the effect of gate electrodes is revealed. By analyzing the transmission spectra, we find that gate voltages change the position of energy levels of nanowires, and thereby modulate the current of nanowire devices. This work provides a deep insight into the effect of substitutional position on the electron transport properties of ultrathin Si nanowires.