I have measured the surface-map of two SiC samples (both polished) with Zygos NewView instrument.

One sample is from Kyocera and the other one from a cheaper company. For both samples it is actually quite difficult to measure the rms roughness as in both samples, the surface is featured by a lot of holes, partly having depths of 2-6 mum. Therefore, I got rms values ranging from 1 to 10 nm for both samples. Nevertheless, from the maps itself one can get the conclusion that kyoceras polishing (the first picture) is better as, apart from the holes, it looks smoother.