Impurity incorporation during sublimation bulk crystal growth of 6H- and 4H-SiC

The impurity incorporation behavior during sublimation growth of 6H- and 4H-SiC has been investigated. There is an increase in nitrogen incorporation from (0001)Si to (<11(2)over bar 0>) to (<1(1)over bar 00>) to (<000(1)over bar>)C, while boron is preferentially incorporated on (0001)Si. For growth on (<000(1)over bar>)C, a polytypic dependence of impurity incorporation was observed: 6H-SiC crystals always incorporate more nitrogen and less boron than 4H-SiC crystals. Atomic force microscope (AFM) observations revealed that there is a marked difference in the growth morphology between 6H-SiC(<000(1)over bar>)C and 4H-SiC(<000(1)over bar>)C, A discussion is given of the origin of the observed polytypic dependence of impurity incorporation with reference to the growth surface morphology.