Understanding and Improving Defects in Silicon Carbide Semiconductor Devices

Open Access
Storey, Matthew Joseph
Area of Honors:
Engineering Science
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Patrick M Lenahan, Thesis Supervisor
  • Bernhard R Tittmann, Honors Advisor
  • Judith A Todd, Faculty Reader
  • SiC
  • defect density
  • semiconductor
  • silicon carbide
  • electrical measurement
Silicon (Si) has long been the leader in the semiconductor market covering a wide range of applications. Research efforts are attempting to replace silicon devices with those made from silicon carbide (SiC), especially in high frequency, high temperature, and high power applications. Currently, these SiC devices have detrimental limiting factors, which can be attributed to the high number of defects at the SiC-SiO2 interface. These defects are created during the manufacturing process. A comprehensive study of these defects needs to be done so that connections and alterations can be made to the manufacturing processes, leading to fewer defects in these SiC devices. Electrically Detected Magnetic Resonance (EDMR) studies were previously done in the lab and the majority of the defects are suspected to be silicon vacancies. In this thesis, capacitance-voltage electrical measurements were taken and used to examine defect densities in several SiC devices using the Gray-Brown and Jenq technique. The initial n-type 4H-SiC MOS thin oxide capacitors were not suited for the aforementioned electrical techniques. Instead, n-channel 4H-SiC MOSFETs with NO annealed and dry oxides were studied. The Jenq technique showed larger average defect densities in the dry oxide device, which is consistent with EDMR results done in the lab. The Gray-Brown method, on the other hand, was qualitatively indicative of similar behavior, but unresolved problems with accumulation capacitances limited the usefulness of that data.