Unintentional incorporation of contaminants during chemical vapour deposition of silicon carbide

6H SiC layers were grown by chemical vapour deposition. The contents of nitrogen, aluminum and boron contaminants were determined by secondary ion mass spectroscopy. The incorporation of these elements leads to unintentionally p-type layers when growth is performed on uncoated graphite susceptors. The use of coated susceptor materials yields n-type layers. The lowest achieved doping levels are determined by capacitance-voltage measurements to be NA − ND = 1 × 1014 cm−3 and ND − NA = 4 × 1015 cm−3. An attempt is made to explain the observed doping mechanism using a recently proposed model of “site competition” during epitaxial growth.