All ETDs from UAB

Advisory Committee Chair

Mary Ellen Zvanut

Advisory Committee Members

Joseph Harrison

Jack Lancaster

Document Type


Date of Award


Degree Name by School

Master of Science (MS) College of Arts and Sciences


Due to its physical and electrical properties, silicon carbide (SiC) has attracted much attention recently for its possible applications in high power devices. Point defects and the associated defect levels are important to understand if we are to produce high quality SiC wafers. While a lot has been done to understand point defects using electrical measurements, electron paramagnetic resonance (EPR) reveals more detailed information. EPR gives us both the number of defects and also their specific structure and charge state while photo-EPR helps to determine their defect level. EPR measurements were done at 80 K in the dark and during illumination. The defect we are studying is SI5, a carbon vacancy carbon antisite pair. Previous photo-EPR measurements showed one SI5 defect level, VCCSi--/-, is 0.8 ± 0.05 eV below the conduction band edge and is thought to undergo a double negative to single negative charge transition upon illumination. A second defect level, VCCSi-/0, is thought to be located below 0.8 eV from the conduction band edge , and represents a neutral to single negative charge transition when illuminated. Using a wide range of samples with different activation energies, we have interpreted photo-EPR data in terms of a model that incorporates the three SI5 charge states and the positively charged carbon vacancy, VC+. According to the model, a carbon vacancy defect level is about 2.25 eV below the conduction band edge, and is thought to represent a single positive to double positive iii charge transitions upon illumination. Photo-EPR results indicate that SI5 and VC+ might be involved in charge compensation.



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