This paper investigates the punch-through phenomenon in SiC Schottky Barrier Diodes (SBD) from capacitance-voltage (C-V) characteristics at high reverse bias voltage. High voltage bias application has not been possible by conventional measurement instrumentation. The authors, therefore, develop C-V characteristics measurement instrumentation which enables the application of high dc bias voltages on SiC-SBD up to the rated reverse blocking voltage. The measurement is then validated through the comparison of results from different measurement methods. The proposed methods clearly reveal the punch-through phenomenon of measured SiC-SBD, and enable the extraction of pertinent parameters for device modeling.