Examination of Defect-Induced Properties in Nanomaterial Systems

Thesis (Ph.D.)--University of Washington, 2021Doped, semiconducting nanomaterial systems can be widely used for sensing, spintronic,light harvesting, and display applications to name a few. The ability to tune the response of these systems through modulation of their size or the inclusion of specific atoms and defect centers enables many of these applications. An in-depth understanding of the origin of observed responses, as well as the prediction of the performance of novel systems is highly sought-after. Density functional theory (DFT) is a fairly accurate method which enables examination into systems approaching the experimental size of nanoparticles. In the first part of this work, the spectroscopic signatures of dopants within a nanodiamond lattice are examined. Since nanodiamonds are wide-band-gap semiconductors with a rigid lattice that are stable under large temperatures and pressures, they are an excellent candidate for several applications such as high pressure and temperature sensors. The abiltiy to control the doping within the lattice enables the design of defects with long lasting coherence enabling their use as spin sensors or qubits. The spectroscopic signatures of several of these dopants are examined to see the effects on the vibrational, optical, and X-ray absorption spectroscopies to inform on the structure of these systems, and provide methods for their identification within a given sample. The second part investigates how atomically percise chemical doping can create and control complex magnetic patterns within a 2-D magnetic device