Exciton Dynamics and the Electronic Structure of CdSe/ZnSe Quantum Dots

University Of Cincinnati Main Campus, Cincinnati OH

Investigators

Abstract

This condensed matter physics project utilizes time-resolved spectroscopies, and high spatial- and energy-resolved spectroscopies to probe the static and dynamic character of electronic states of individual CdSe/ZnSe self-assembled quantum dots. The excited state structure of the electronic levels will be probed by resonant, Raman and photoluminescence spectroscopies. Polarized photoluminescence and magnetic field effects will be used to identify the symmetry properties of the states. Dynamics of transitions among the quantum dot electronic states are studied by time-resolved photoluminescence or pump-probe picosecond/femtosecond excitations. Of particular interest is the physics of interactions between closely associated quantum dots as well as interactions of excitations with optic and acoustic photons. The undergraduate and graduate students involved in this research will be trained in modern state-of-the-art techniques for synthesizing and characterizing nanostructured materials. %%% This condensed matter physics project use optical methods to electrons and holes which are confined to nanostructures where the length scale is comparable to the wave nature of the particles. Such quantum dots can be made by utilizing the tendency of nature to 'self organize' itself. Just as dew does not continuously wet a leaf but often organizes into a layer of droplets, cadmium sulfide when deposited on a zinc selenide surfaces forms small nanoscale solid particles which are know as quantum dots because of their small size. Extensive experiments in recent years have shown that these structures confine electrons to states that are reminiscent of the electron states in atoms or molecules. The electronic states in the quantum dots are not as well understood as the molecular electronic states, ant the quantum dot states can potentially be tuned by varying the size and composition of the dots. This project will largely use high resolution optical techniques to probe the energy structure and dynamics of electrons in the quantum dots. Graduate students and undergraduate students associated with the project will be trained in state-of-the-art techniques for making and characterizing nanostructured materials.