Discipline: Technology and Engineering
Subcategory: Electrical Engineering
Vivian Zhou - Case Western Reserve University
Silicon carbide (SiC) is a promising material for use in electronics due to its inherent large band gap. The renewed interest in this material is largely a result of advancing technology and the demand for semiconductor devices that operate in extreme temperature and power conditions. In addition to conventional electronics, SiC possesses great potential for quantum computing. Rapid developments in quantum computing technology have incentivized the study of reliable qubit, specifically nitrogen-vacancy (NV) center in diamond. Because diamond qubits can be initialized, manipulated, and measured at room temperature, this allows quantum computing without super cooling. Since high quality diamond cannot be produced in large quantities and processing techniques are still premature, it has been a roadblock so far. SiC, on the other hand, is available in high-quality single crystals and has a molecular structure very similar to diamond, thus it is a promising material to examine NV-like defects. In order to appreciate the advantages of SiC and utilize its properties for emerging applications, it is desirable first to understand the molecular structure and quality of the material.
In this study, we employed Raman spectroscopy and carefully extracted useful information on SiC such as disorder, lattice strain/stress, defects and doping concentration. We worked specifically with one polytype, 3C-SiC, on this study to demonstrate the reliability of Raman spectroscopy as an optical method of SiC characterization. We are testing both single crystal and poly SiC grown on various substrates like silicon (Si), silicon dioxides (SiO2) and silicon nitrides (SiN) to explore the effects of substrate on Raman signatures. We are also measuring 3C-SiC diaphragms with thickness variation to remove signal from substrate and study variation in thickness and stress on the system. Specifically, we have carefully resolved the slight shifts in Raman peaks, change in line widths and change in peak intensity and investigated correlated material properties of 3C-SiC such as defects, doping and stress in the material. We also performed Raman mapping of certain areas to search for NV center defect locations, and intensity ratios for sample quality. Future steps will include Raman measurements of dynamic systems like resonance of oscillating SiC membranes and bulging.
T. Kimoto and J. A. Cooper, Fundamentals of Silicon Carbide Technology, John Wiley & Sons Singapore Pte. Ltd., Solaris South Tower, Singapore, 2014
J. R. Weber, W. F. Koehl, J. B. Varley, A. Janotti, B. B. Buckley, C. G. Van de Walle, and D. D. Awschalom, Journal of Applied Physics 109, 102417 (2011)
Funder Acknowledgement(s): I thank P. Feng for advice on this project. Funding was provided by an NSF EFRI.
Faculty Advisor: Philip Feng, firstname.lastname@example.org
Role: I participated in a large part of the literature review to compile existing information on the Raman spectra of 3C-SiC and the types of common defects found in this material. I have also done extensive research regarding NV center like defects in SiC and their application to quantum computing. The measurements taken in the study were also done by me with help from my mentor in terms of familiarizing myself with the equipment in the lab.