Semiconductor Carrier Dynamics in Metal-Semiconductor Nanostructures

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Technical Description: This project is designed to utilize unique materials growth techniques to investigate the optical properties and the underlying science of metal-semiconductor hybrid nanostructures. Photoluminescence spectroscopy and photoluminescence excitation spectroscopy of quantum dots and quantum wells are used to probe the nature of the interaction between surface plasmon polaritons and excitons. The principal investigator and students use these optical techniques to observe and control the coherent transfer of energy across the interface between metal and semiconductor materials, as a function of growth parameters. In addition, frequency-resolved optical gating spectroscopy combined with spectral interferometry yield a sensitive method for temporal characterization. The material systems being studied are silver, gallium, aluminum, and indium metal nanoparticles and indium arsenide and indium gallium arsenide quantum wells and dots. The research project designs, fabricates, characterizes and investigates the origin of the linear and non-linear optical behavior of hybrid metal-semiconductor nanostructures.Non-technical Description: In its simplest form, a surface plasmon polariton is an electromagnetic wave that is guided and confined along a metal-dielectric interface much in the same way that light can be guided by an optical fiber. This confinement leads to an intense electromagnetic field at the interface, resulting in an extraordinary enhancement of materials properties. This is particularly true when the separation between metal and dielectric materials is at the nanoscale. In this project, using novel materials fabrication techniques, the functionality of metal-semiconductor hybrid nanostructures is increased to demonstrate control of light waves on a nanometer length scale and ultra-short optical switching times. As a result, the confined nature of propagating surface plasmon polariton waves enables all-optical integrated circuits. One can imagine tiny active photonic elements based on nonlinear surface plasmon polariton optics that allows propagation and switching of nanoscale light beams confined by the metal-semiconductor interface. In addition to the potential for technology impact, the project gives students the skills to design and fabricate nanostructures, characterize their morphology and utilize their data to question and advance the understanding of the exciton-surface plasmon polariton coupling. In this way, students uncover novel and useful optical behavior while learning exciting techniques in both continuous wave and ultra-fast optical spectroscopy.