Effect of inclined quantum wells on macroscopic capacitance-voltage response of Schottky contacts: Cubic inclusions in hexagonal SiC

Finite-element calculations of Schottky diode capacitance-voltage (C-V) curves show that an array of subsurface inclined quantum wells (QWs) produce negligible change in shape and slope of C-V curves, but significantly reduce the intercept voltage. This is particularly important for hexagonal SiC, in which current- or process-induced cubic inclusions are known to behave as electron QWs. These calculations naturally explain the surprisingly large effect of cubic inclusions on the apparent 4H-SiC Schottky barrier determined by C-V measurements, and together with the measured C-V data indicate the QW subband energy in the inclusions to be ~0.51 eV below the host 4H-SiC conduction band.