Owing to the minute sizes of nanostructures, even minor imperfection in the shape of the end of the nanostructures would result in large variations in the semiconducting properties.
Nanoribbon structure isolated from bulk crystal
In order to address this issue, researchers at the Institute for Functional Nanomaterials (IFN) have come up with a novel idea of looking at some natural structures and their lattices for a solution. The researchers considered antimony selenide and antimony sulphide crystals for the study. The results of their experiments were published in the journal Nanotechnology, which provided an in-depth analysis of the similarity in the atomic structure of the two substances. The structures were made up of nanoribbons 1 nm wide and 0.2 nm thick and were loosely bound to each other.
The research team then isolated the ribbons and studied them in-detail and made calculations of their stability. The report concluded that the structure of the nanoribbons exhibited a nearly perfect surface as there were no dangling bonds present. The energy gap between the ribbons was well defined, the value for antimony selenide was 1.66 eV and for antimony sulphide it was 2.16 eV. The study also revealed that the two crystals could be interfaced to build ribbons that form a semiconducting heterostructure of perfect sub-10 nm. The valance band exhibited graded straddling type behaviour, whereas the conduction band presented an abrupt straddling type of behaviour. Hence, intrinsic electrons and holes migrate from antimony selenide to the interface giving rise to a modulated charge distribution which is in equilibrium along the length of the heterostructure.
Source: http://www.ifn.upr.edu/people/9-carlos-mar-n/