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.
