Magneto-optical studies of HgTe/HgxCd1-xTe(S) core-shell nanocrystals.
ABSTRACT The synthesis and magneto-optical properties of HgTe nanocrystals capped with HgxCd1-xTe(S) alloyed shells have been investigated. The magneto-optical measurements included the use of optically detected magnetic resonance (ODMR) and circular polarized photoluminescence (CP-PL) spectroscopy. The PL spectra suggest the existence of luminescence events from both the core HgTe and the HgxCd1-xTe(S) shells. The continuous-wave (cw) and time-resolved ODMR measurements revealed that the luminescence at the shell regime is associated with a trap-to-band recombination emission. The electron trap is comprised of a Cd-Hg mixed site, confirming the existence of an alloyed HgxCd1-xTe(S) composition. The ODMR data and the CP-PL measurements together revealed the g-values of the trapped electron and the valence band hole.
- Journal of Materials Chemistry 12/2009; · 5.97 Impact Factor
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ABSTRACT: The review describes the studies of the magneto-optical properties of II-VI and III-V semiconductor nanocrystals (NCs) capped with organic or inorganic epitaxial shells. The investigations focused on the chemical identification of localization sites (core, shell, or interface) of photogenerated carriers in spherical NCs and elucidated the influence of the surface/interface quality on the optical properties of the materials. Optically detected magnetic resonance (ODMR) spectroscopy was used for the study of the proposed physical properties. The ODMR method provides the means to identify the surface/interface sites and correlate them with specific optical transition. In addition, this method reveals information about the spin multiplicity of band edge and trapped states and the electron-hole exchange interaction, determines the spectroscopic g-factors, distinguishes between the radiative and nonradiative characteristic of a trapping site, and evaluates the spin-lattice relaxation times.Annual Review of Physical Chemistry 02/2004; 55:509-57. · 13.37 Impact Factor
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ABSTRACT: The chemistry, material processing and fundamental understanding of colloidal semiconductor nanocrystals (quantum dots) are advancing at an astounding rate, bringing the prospects of widespread commercialization of these novel and exciting materials ever closer. Interest in narrow bandgap nanocrystals in particular has intensified in recent years, and the results of research worldwide point to the realistic prospects of applications for these materials in solar cells, infrared optoelectronics (e.g. lasers, optical modulators, photodetectors and photoimaging devices), low cost/large format microelectronics, and in biological imaging and biosensor systems to name only some technologies. Improvements in fundamental understanding and material quality are built on a vast body of experience spread over many different methods of colloidal synthetic growth, each with their own strengths and weaknesses for different materials and sometimes with regard to particular applications. The nanocrystal growth expertise is matched by a rapidly expanding, and highly interdisciplinary, understanding of how best to assemble these materials into films or hybrid composites and thereby into useful devices, and again there are many different strategies that can be adopted. In this review we have attempted to survey and compare the recent work on colloidal synthesis, film and nanocrystal composite material fabrication, concentrating on narrow bandgap chalcogenide materials and some of their topical applications in the solar energy and biological fields. Since these applications are attracting rising interest across a wide range of disciplines, from the biological sciences, device engineering, and materials processing fields as well as the physics and synthetic chemistry communities, we have endeavoured to make the review of these narrow bandgap nanomaterials both comprehensive and accessible to newcomers to the area.Chemical Society Reviews 01/2013; · 24.89 Impact Factor