Surface gradient dependence of bandgap energy and dielectric constant of ZnO tapered nanowires.

In order to gain a better understanding of the surface gradient effect on the electronic properties of ZnO tapered nanowires (TNWs), we establish an analytical relationship to elucidate the band offset and dielectric change by considering the joint effect from the nanowire size and surface gradient based on the atomic-bond-relaxation correlation mechanism and the Kramers-Kronig relation. It is found that a pronounced blue shift of the bandgap and dielectric suppression of ZnO TNWs are shown compared to those of NWs with a cylindrical shape. Our results are validated by comparing them with the available evidence, suggesting that the developed method is helpful for shape design on tunable electronic properties of nanostructures. [ABSTRACT FROM AUTHOR]