Quantitative Characterization of Surface Polarity Dependence of Wetting Properties of V-Doped SiC Using a Novel Image Analysis Technique

Abstract

Vanadium doped semi-insulating (SI) 6H-SiC {0001} substrates and their wetting properties were characterized using precisely dispensed de-ionized (DI) water drops. Radius, contact angle, width (chord), height and cap volume of a DI water drop on the SiC surface were quantitatively determined by analyzing sideview images of DI water drop in contact with SI 6H-SiC {0001} substrates using image processing software. The average of ten (10) contact angle measurements showed approximately 4 ° difference between the Si-face (48.48°) and the C-face (44.33º). Contact angle on the Si-face (0001) measured after native oxide removal showed significant decrease of contact angle, from 55° to 25° and recovered over time by room temperature oxidation in air. In contrast, contact angle on the C-face (000-1), measured after native oxide removal, showed significant increase of contact angle, from 40° to 54°, and continue to increase contact angle up to 71° after room temperature oxidation for 24 hours in air. Contact angle is found to be very sensitive to SiC surface polarity and specific surface conditions. Contact angle measurement, using image analysis techniques, can be applied as an in-line identification and surface condition characterization technique for SiC polytypes of specific surface polarities.