3C-SiC p-type epilayers were grown to thicknesses of 1.5, 3, 6 and 10 μm on 2.5° off-axis
Si(001) substrates by chemical vapor deposition (CVD). Silane and propane were used as precursors.
Structural analysis of epilayers was performed using transmission electron microscopy (TEM),
high-resolution x-ray diffractometry (HRXRD), and Raman spectroscopy. TEM showed defect
densities (stacking faults, twins and dislocations) decreasing with increasing distance from the SiC/Si
interface as the lattice mismatch stress is relaxed. This observation was corroborated by a monotonic
decrease in HRXRD peak width (FWHM) from 780 arcsecs (1.5 μm thick epilayer) to 350 arcsecs (10
μm thick epilayer). Significant further reduction in x-ray FWHM is possible because the minimum
FWHM detected is greater than the theoretical FWHM for SiC (about 12 arcsecs). Raman
spectroscopy also indicates that the residual biaxial in-plane strain decreases with increasing epilayer
thickness initially, but becomes essentially constant between 6 and 10 μm. Structural defect density
shows the most significant reduction in the first 2 μm of growth. Phosphorus implantation was used
to generate n+/p junctions for the measurement of the critical electric field in 3C-SiC. Based on
current-voltage analyses, the critical electric field in p-type 3C-SiC with a doping of 2x1017 cm-3 is
1.3x106 V/cm.
Electric‐field‐induced Raman spectroscopy
