Articles written in Pramana – Journal of Physics

    • The electronic and transport properties of Li-doped graphene nanoribbons: An ab-initio approach


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      The metal-to-semiconductor transition has been noticed in graphene nanoribbons (GNRs) with various novel electronic and structural characteristics. The prospective and scope of GNRs for an array of implications could be spread significantly by this transition. Based on density functional theory (DFT) calculations, we studied the electronic and transport properties of zig-zag GNRs doped with lithium (Li) along with different edge morphology. Zig-zag nanoribbons are known to exhibit metallic behaviour without using spin. The structural properties, namely, edge state, doping and ribbon width, can be considered to affect the electronic properties of GNR structures. In this study, the changes in the electronic properties by doping a Li atom with various atomic percentages (16.6%, 33.3%, 50% and 66.6%) were investigated. Calculations were done by employing the local density approximation (LDA) based on DFT. In the presence of unique edge states, the edge-modified systems exhibit a noticeable change with prominent and better Li mobility. As a result, it has been observed that substituting two Li atoms at the carbon edges is more predominant compared to other doping configurations. We expect that our peculiar results will have potential applications in energy conversion, solar cells and thermoelectric devices.

    • Effect of strain on the structural and electronic properties of transition metal-doped arsenene nanoribbons: An ab-initio approach


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      Recently, arsenene, having a monolayer honeycomb structure of grey arsenic, has been manufactured successfully. Motivated by this, here we have calculated the electronic properties and stability of arsenene by employing the first-principles method for calculations. We have considered two different structures, namely planar and puckered. Based on the analysis, the puckered structure was found to be semiconducting in nature. Additionally, we have estimated the electronic properties of different 3d transition metal (TM) atoms doped in arsenene. Here, straining the nanoribbons also modulates the band gap. It closes the band gap for puckered arsenene under the 8% strain application. Specifically, a 4% strain is considerably sufficient to transform metallic arsenene to a directband-gap semiconductor. Also, the bond angle between the nearest atoms becomes almost equal. We have observed that Ni-doped arsenene is the most stable. We have also studied the electronic band structures of the pristine and TM-doped antimonene. Planar antimonene is metallic while rhombohedral antimonene is semiconducting. Our results will play vital roles in sensors and various nanoelectronics applications.

    • Electronic and transport properties of chemically functionalised zig-zag graphene nanoribbons: First principle study


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      In this work, we have performed the chemical functionalisation of metallic graphene nanoribbons (GNRs) with different functional groups. The analysis of graphene in terms of relative stability and electronic properties has been done. The HOMO–LUMO gaps are quantitatively analysed to reveal the influence of different functional groups including hydroxyl, carboxyl and hydrogen sulphide groups. Interestingly, the influence of edge functionalisation on the HOMO–LUMO gap of zig-zag graphene nanoribbons (ZGNRs) presents significant change using density functional theory (DFT). Understanding the electronic properties in terms of density of states and band structure of functionalised graphene is of great relevance today. It is found that the geometrical structures and electronic properties of the GNRs could be significantly changed with the oxygen containing group. With the carboxyl-functionalised GNRs, the interaction leads to a decrement in the HOMO–LUMO gap of graphene. This fact makes GNR a possible candidate for nanoelectronic devices.

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