Growth of SiC epitaxial layers on porous surfaces of varying porosity

The presence of micropipes and dislocations in SiC wafers used as substrates for SiC epitaxial growth may cause formation of lattice defects in the epi layers. In previous research, optical and electrical characterization of epitaxial layers grown on porous substrates consistently indicated an improvement in the material quality over conventional substrates. Both the mechanism(s) for this improvement as well as the optimum porous composition to maximize material quality is a topic of intense interest. To provide insight into the optimum porous layer composition two 2 in. 4H–SiC(0 0 0 1) 8° off-axis SiC substrates were processed to form 1 cm regions (stripes) across each substrate, with each stripe having been subjected to different anodization conditions. For both samples the last stripe was left unanodized to serve as a control sample. CVD growth was then conducted to produce a 3–4 μm thick n-type epitaxial layer. Raman spectroscopy, C–V, X-ray diffraction and topography, and photoluminescence spectroscopy were conducted on the stripes to determine the difference in epi character as a function of porous composition.