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.
[Show abstract][Hide abstract] ABSTRACT: Thesis (Ph. D.)--Oklahoma State University, 2007. Includes bibliographical references. Vita. The full text of the dissertation is available as an Adobe Acrobat pdf.file (xiii, 148 p.); Adobe Acrobat Reader required to view the file.
[Show abstract][Hide abstract] 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.
[Show abstract][Hide abstract] ABSTRACT: This study describes a direct measurement of spectroscopic g-factors of photo-generated carriers in InP/ZnS and HgTe/HgxCd1−xTe(S) core–shell nanocrystals. The g-factor of trapped electrons and their spin-lattice versus radiative relaxation ratio (T1/τ) were measured by the use of continuous-wave and time-resolved optically detected magnetic resonance (ODMR) spectroscopy. The g-factors of excitons and donor–hole pairs were derived by the use of field-induced circular-polarized photoluminescence (CP-PL) spectroscopy. The combined information enabled to determine the g-factors of the individual band-edge electrons and holes. The results suggested an increase of the g-factor of the exciton and conduction electron with a decrease of the nanocrystal size.
Physica E Low-dimensional Systems and Nanostructures 02/2005; 26(1):9-13. DOI:10.1016/j.physe.2004.08.013 · 2.00 Impact Factor
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