A comparative and a systematic study on the effects of B, N doping and C-atom vacancies on the band gap in narrow zig-zag graphene nanoribbons via quantum transport calculations

•DFT with NEGF is used to study electronic and transport properties of ZGNR.•Site I, II and III are selected for defects and doping which lies at its edge.•Mono/Di vacancy defects and B/N doped is comparatively and systematically studied.•ZGNR's semi-metallic nature is converted to semiconductor, opening bandgap >0.4 eV.

Density functional theory(DFT) coupled to non-equilibrium green's function has been performed to explore avenues to open band gap in graphene nanoribbons in order to reach a high current on/off ratio for their potential applications in transistors and futuristic nanodevices. Introduction of defects such as C-atom vacancies and doping with elements lying on either side of carbon in the periodic table have been invoked to engineer the band gap in narrow zig-zag nanoribbons. By varying the concentration of B and N dopants in zig-zag nanoribbon (ZGNR), their electronic structure is transformed to that of p-type and n-type semiconductor. A maximum band gap of 0.98 eV, 0.88 eV and 0.89 eV is achieved upon incorporating carbon-atom vacancies, boron doping and nitrogen doping respectively. Transport properties have been analyzed through the calculation of transmission spectrum and I-V characteristics. Doped and defective ZGNRs reported herewith show non-linearity in the current-voltage characteristics. The highest current value achieved by doping and defect is 16.5,39 μA for boron dopant, 18, 27 μA for nitrogen and 25.5, 30.2 μA for defects.

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