University of Delaware - College of Engineering



Terahertz Spectroscopy of Doped Nanostructures

James Kolodzey

This project addresses an experimental and theoretical study of the synthesis and properties of nanostructures that have multiple doped regions that are in contact with regions of different doping, in silicon-germanium (SiGe) based materials. The goal is to identify mechanisms governing the formation of nanostructures that are doped with shallow acceptors, in contact with regions having shallow donors, and the underlying transport and radiative transitions between localized and resonant states, the band continuum, and between other doped regions on the nanoscale. This research seeks to understand how the synthesis of doped SiGe nanostructures depends on interfaces, composition, strain, and neighboring dopants. Such multiple doped nanostructures can be formed during molecular beam epitaxy by interrupting growth, changing the dopant type and continuing the growth with another set of nanostructures. The impurities in nanostructures will be characterized by techniques including temperature dependent terahertz radiative emission spectroscopy, current versus voltage measurements, and atomic force microscopy. If successful, this research will give an improved understanding of dopants in nanoparticles that are surrounded by regions with different dopants, in the SiGe based materials system. This research may have important technological consequences because the understanding of doping in structures is pivotal to the operation of devices and circuits.

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