Probing Carrier Dynamics in Novel Metal/Semiconductor Nanocomposites

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Technical AbstractNanocomposites in which semimetallic rare-earth-monopnictide (RE-V) nanoparticles are epitaxially embedded within III-V semiconductors are an exciting new class of electronic materials. The unique properties of these nanocomposites have already led to improved performance in prototype devices ranging from thermoelectrics to tunnel junctions. Despite this progress, the fundamental nanoscale physical properties of these nanocomposites remain poorly understood. For example, both the source of carriers and the interfacial contributions to charge transport and energy relaxation remain unknown. In this grant, well-characterized InAs quantum dots will be used as a local probe of the properties of single RE-V nanoparticles. The single nanoparticle spectroscopy will be complemented by ensemble ultrafast optical and terahertz spectroscopy. The ultrafast measurements will quantify the dynamic properties of the nanocomposites while the single nanoparticle spectroscopy will enable development of a microscopic theory of material properties. In addition to allowing measurements of single nanoparticles, the incorporation of quantum dots will provide a new tool for unprecedented control over growth morphology and the production of radically new nanocomposite structures.Non-Technical AbstractThis grant supports efforts to fundamentally understand a technologically-relevant nanocomposites system. The comprehensive understanding of nanoscale physical properties developed through this grant will lead directly to practical applications with far-reaching impacts, including improved energy harvesting devices and significant advances in terahertz science and technology. Two graduate students will be exposed to a highly interdisciplinary environment, and K-12 students in local schools will benefit from teacher training activities and also the creation of educational equipment that will be loaned to local schools.