Size-dependent exciton recombination dynamics in single CdS nanowires beyond the quantum confinement regime
Sum, Tze Chien
Date of Issue2013
School of Electrical and Electronic Engineering
Energy Research Institute
A deep understanding of the size, surface trapping, and scattering effects on the recombination dynamics of CdS nanowires (NWs) is a key step for the design of on-demand CdS-based nanodevices. However, it is often very difficult to differentiate these intertwined effects in the NW system. In this article, we present a comprehensive study on the size-dependent exciton recombination dynamics of high-quality CdS NWs (with diameters from 80 to 315 nm) using temperature-dependent and time-resolved photoluminescence (TRPL) spectroscopy in a bid to distinguish the contributions of size and surface effects. TRPL measurements revealed two distinct processes that dominate the band edge recombination dynamics—a fast decay process (τ1) originating from the near-surface recombination and a slower decay process (τ2) arising from the intrinsic free exciton A decay. With increasing NW diameters, τ1 increases from 0.10 to 0.42 ns due to the decreasing surface-to-volume ratio of the NWs, whereas τ2 increases from 0.36 to 1.21 ns due to decreased surface scattering in the thicker NWs—as validated by the surface passivation and TRPL studies. Our findings have discerned the interplay between size and surface effects and advanced the understanding of size-dependent optoelectronic properties of one-dimensional semiconductor nanostructures for applications in surface- and size-related nanoscale devices.
DRNTU::Science::Chemistry::Physical chemistry::Quantum chemistry
Journal of physical chemistry C
© 2013 American Chemical Society. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of physical chemistry C, American Chemical Society. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at DOI: [http://dx.doi.org/10.1021/jp312850w].