Type-II Quantum Dots:  CdTe/CdSe(Core/Shell) and CdSe/ZnTe(Core/Shell) Heterostructures

• Published in: Journal of the American Chemical Society Vol. 125; no. 38; pp. 11466 - 11467
• Main Authors: Kim, Sungjee, Fisher, Brent, Eisler, Hans-Jürgen, Bawendi, Moungi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 24-09-2003
• Subjects: Cadmium Compounds - chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Exact sciences and technology; Ii-vi semiconductors; Luminescent Measurements; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics; Quantum dots; Quantum Theory; Selenium - chemistry; Spectrum Analysis - methods; Tellurium - chemistry; Zinc - chemistry; Zinc tellurides; Photoluminescence; Transition elements Compounds; Experimental study; Cadmium selenides; Semiconductor quantum dots; Transmission electron microscopy; II-VI semiconductors; Cadmium tellurides; Luminescence spectrometry; Transport processes; Carrier mobility; Carrier density
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0361749

Type-II band engineered quantum dots (CdTe/CdSe(core/shell) and CdSe/ZnTe(core/shell) heterostructures) are described. The optical properties of these type-II quantum dots are studied in parallel with their type-I counterparts. We demonstrate that the spatial distribution of carriers can be controlled within the type-II quantum dots, which makes their properties strongly governed by the band offset of the comprising materials. This allows access to optical transition energies that are not restricted to band gap energies. The type-II quantum dots reported here can emit at lower energies than the band gaps of comprising materials. The type-II emission can be tailored by the shell thickness as well as the core size. The enhanced control over carrier distribution afforded by these type-II materials may prove useful for many applications, such as photovoltaics and photoconduction devices.