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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