Residual damage effects on gate contacts formed on SiC surfaces etched by using the amorphization technique |
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Authors: | Dev Alok K Makeshwar B Jayant Baliga |
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Affiliation: | (1) Power Semiconductor Research Center, North Carolina State University, 27695 Raleigh, NC |
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Abstract: | A trench fabrication process has been proposed and experimentally demonstrated for silicon carbide using the amorphization
technique. In the present work, the quality of gates oxide for metal oxide semiconductor field-effect transistors (MOSFETs)
and Schottky barrier contacts for metal semicondcutor field-effect transistors (MESFETs)] fabricated on the etched surfaces
are compared with those formed on the as-grown silicon carbide surface. The resistivity and breakdown electric field of the
thermal oxide grown on the etched surface was found to be comparable to that of thermal oxide grown on silicon. However, a
large concentration of acceptor type interface states (0.5-1 x 1013 cm−2eV−1) was observed. This results in a large negative interface charge at room temperature and a significant shift in flat band
voltage as a function of temperature, which makes the process unsuitable for formation of gates in UMOSFETs. Titanium Schottky
contacts formed on the etched surface showed superior reverse current-voltage characteristics and higher breakdown voltages
than the Schottky diodes formed on unetched surface with similar doping concentrations. This indicates that the argon implant
process for trench formation is suitable for fabrication of gate regions in high voltage vertical MESFETs (or SITs). |
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Keywords: | Etching Schottky silicon carbide thermal oxide |
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