On substitution of Au at center of the ribbon, the MDV 3100 gap increases to 0.8 eV, whereas substituting Au at both edges of the ribbon reduces the band gap thus turning the GNR into a metallic one. It is found that the edge substitution alters the band gap, promoting the onset of semiconductor–metal transitions. We also find that the band gap variation is insignificant due to Au-adsorption at investigated sites; instead the energy gap is more sensitive to the substitution of Au in the AGNRs. Besides the nature and presence of dopants within the nanoribbons, the mode of doping and location of these dopants within the ribbons are important in order to modify their properties.
3.3. Transport properties
Transport properties of GNRs depend strongly on whether asteroid impacts have an armchair or zigzag edge. It is well known that an armchair edge does not induce local edge magnetism , and therefore in this work, we seek to probe the scope of spin-polarized transport in Au-doped AGNRs. In the present study, we use I–V curves as a way to understand the electrical transport properties of these ribbons and compare the results obtained with non-spin polarized calculations. To further explore the transition from semiconductor to metal, and understand the extent of spin injection due to Au-doped AGNRs, we plotted the calculated I–V characteristics for these two probe devices with the bias voltage varying from 0 to 2 V, as detailed in Fig. 9 and Fig. 10.