Date of Award
Doctor of Philosophy (PhD)
Electrical and Computer Engineering
Ronald Coutu, Jr.
Quantum defects in thin film structures are a promising avenue for quantum applications. These defects, often resulting from structural anomalies lead to distinct electronic and optical characteristics within the host material. The absence of atoms in a crystal structure, commonly known as crystal vacancies, can significantly modify a material's quantum properties. This research investigated cost-effective materials compatible with complementary metal oxide semiconductor (CMOS) processes that possess quantum defects feasible for room-temperature operations. The approach encompasses a thorough evaluation of the potentialities of AlN, Al2O3, and SnOx for quantum-enhanced applications. Initially, we deposited thin films of AlN, Al2O3, and SnOx onto silicon (Si) substrates via radio frequency (RF) magnetron sputtering. These depositions were performed under controlled temperature conditions spanning from 25°C to 400°C. Surface characterization was conducted to ensure quantum information reliability. To deliberately introduce defect sites within the films, the approach employed two novel fabrication techniques: indentation patterning and etch patterning. The defects were engineered to act as a structured array of angstrom-scale, quantum sites, whose wavefunctions align with those observed in typical material defects. To fabricate the coplanar waveguide (CPW) by MEMS fabrication processes, a meandering structured CPW design ensures the conductor length has an efficient size. For investigating qubit excitation within these defect sites, we introduced RF signals via a CPW. We observed both time-domain and frequency-domain outputs to interpret the patterns of qubit excitation. In our time-domain studies, we discerned notable variations in waveform characteristics, including amplitude, phase, and overall waveform shape. These variations provided valuable insights into qubit excitation and relaxation dynamics. In our frequency-domain experiments, we compared the performance CPWs fabricated using two distinct techniques. The frequency domain analysis revealed no discernible impact of quantum defects buried beneath the CPWs. This research has the potential to pave the way for reliable and economical quantum applications.