Issue 32, 2013

Tuning of band-edges in type-I core–shell nanocrystals through band-offset engineering: selective quantum confinement effect

Abstract

The addition of a shell layer onto semiconducting quantum dots is an approach to control the optical bandgap of core–shell systems. In this direction, we have grown several core–shell nanostructures having a type-I heterostructure configuration. The nature of the energy-offset has been varied by a suitable shell-material with the aim to control the conduction and the valence band-offsets separately. Confined holes or electrons could hence be relaxed selectively leading to an increase in the valence band-edge or a decrease in the conduction band-edge. In this work, after forming such core–shell systems with a control over the shell thickness, we characterized the nanostructures with scanning tunneling spectroscopy in order to determine the density of states and finally the conduction and the valence band-edges of the core–shell systems. We found that while a large band-offset strictly localizes the carriers in the core, a small perturbation indeed delocalizes the carriers up to the shell-layer shifting the relevant band-edge towards the Fermi energy and thereby decreasing the transport gap. The decrease in the transport gap was in agreement with the optical absorption spectra. The results provide a novel route to delocalize a selective type of carrier up to the shell layer of core–shell nanostructured systems.

Graphical abstract: Tuning of band-edges in type-I core–shell nanocrystals through band-offset engineering: selective quantum confinement effect

Article information

Article type
Paper
Submitted
28 Mar 2013
Accepted
14 May 2013
First published
21 May 2013

RSC Adv., 2013,3, 13225-13231

Tuning of band-edges in type-I core–shell nanocrystals through band-offset engineering: selective quantum confinement effect

S. Dey and A. J. Pal, RSC Adv., 2013, 3, 13225 DOI: 10.1039/C3RA41525B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements