Characterization of rare earth and III-V nanostructured materials using experimental and novel data analysis techniques

Doty, Matthew F.In recent years there has been great interest in developing new computing architectures that go beyond Moore’s Law. Such architectures include spintronic and photonic devices that could enable logic functions analogous to CMOS technologies and novel architectures that include quantum information processing. Virtually all emerging device architectures rely on materials with structures on nanometer length scales, either as fundamental units of the computation (e.g. qubits based on the spin projection of electrons or hole confined in quantum dots) or as components of a larger functional material (e.g. ErAs nanoparticles embedded within GaAs heterostructures). It is thus crucial to understand physical phenomena such as charge carrier transfer and many-body interactions within and between these nanostructures. ☐ The objective of this research is to develop and demonstrate statistically-valid methods for characterizing and understanding ErAs nanocomposites and vertically stacked InAs QDMs. Optical studies using time resolved photoluminescence (TRPL) and time-integrated photoluminescence (PL), respectively, investigate the energy structure and charge interactions in these novel nanostructures. Information such as recombination rates of excitons, coulomb interaction terms, and the effect of screening charges can all be extracted from these optical studies. We first demonstrate the use of TRPL to determine the mechanism of charge transfer in ErAs nanoparticles embedded in GaAs coupled with InAs QDs with applications in ultrafast optoelectronic devices. We then demonstrate the first of its kind implementation of Markov Chain Monte Carlo (MCMC) simulations for extracting accurate values for physical parameters from sparse time integrated photoluminescence data from vertically stacked InAs QDs, which are of interest as components of potential quantum computing hardware. This MCMC simulation method provides a template for data analysis of data from other complex spectroscopic techniques. ☐ The methods developed to probe and understand these disparate material systems provide important new tools for the design and development of the next generation of optoelectronic devices.University of Delaware, Department of Electrical and Computer EngineeringPh.D