Abstract
Deterministic band gap in quasi-one-dimensional nanoribbons is prerequisite for their integrated functionalities in high performance molecular-electronics based devices. However, multiple band gaps commonly observed in graphene nanoribbons of the same width, fabricated in same slot of experiments, remain unresolved, and raise a critical concern over scalable production of pristine and/or hetero-structure nanoribbons with deterministic properties and functionalities for plethora of applications. Here, we show that a modification in the depth of potential wells in the periodic direction of a supercell on relative shifting of passivating atoms at the edges is the origin of multiple band gap values in nanoribbons of the same width in a crystallographic orientation, although they carry practically the same ground state energy. The results are similar when calculations are extended from planar graphene to buckled silicene nanoribbons. Thus, the findings facilitate tuning of the electronic properties of quasi-one-dimensional materials such as bio-molecular chains, organic and inorganic nanoribbons by performing edge engineering.
Highlights
For GNRs, where ΔE is the band gap, α is the scaling factor, and w + w ′(Å) is the equivalent width of nanoribbons
The findings facilitate in tuning the electronic properties of quasi-one-dimensional materials such as bio-molecular chains, organic and inorganic nanoribbons by edge engineering, which improve the performance of devices down to molecular level for their wide applications[29,30,31,32,33]
Origin of multiple band gap values in nanoribbons of the same width, same crystallographic orientation, and the same number of the atoms in the supercells is a consequence of modification in the potential profile in the periodic direction, they have practically the same ground state energy
Summary
For GNRs, where ΔE is the band gap (eV), α (eV.Å) is the scaling factor, and w + w ′(Å) is the equivalent width of nanoribbons. Dotted vertical lines are drawn to represent two band gap values for ZGNRs of the same width. Inset figure shows the difference of the ground state energy values for config. II as a function of width for ZGNRs. GNRs. The results are verified when calculations are extended from planar graphene nanoribbons to buckled silicene nanoribbons (SiNRs), GNRs passivated with multiple functional groups at the edges, and rough edged GNRs. the findings facilitate in tuning the electronic properties of quasi-one-dimensional materials such as bio-molecular chains, organic and inorganic nanoribbons by edge engineering, which improve the performance of devices down to molecular level for their wide applications[29,30,31,32,33]
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