The formation of dots by CVD in the hetero-system SiC-Si was studied in the two possible ways : Si dots on SiC substrate and SiC dots on Si substrate. The substrates underwent special surface treatment to reveal a network of parallel steps before deposition of the dots. In the Si on SiC case, the dots density on the 8°off 4H-SiC substrate varied in the range 107 – 7x108 cm-2 and mainly depends on the SiH4 flux and the deposition time. The Si dots are in majority aligned along the step edges of the substrate. In the other hetero-system, only propane was introduced in the reactor to performed a localised carbonisation of the Si(111) 1.5°off substrate. The SiC dots obtained at 1200°C have similar density the Si ones but with smaller size.