Observation of the D-center in 6H-SiC p-n diodes grown by chemical vapor deposition

The D-center in 6H-SiC is a boron-related deep hole trap observed previously in LPE-grown 6H-SiC diodes. We report deep level transient spectroscopy (DLTS) measurements in which the D-center signature is observed in high-purity n- and p-type epitaxial layers formed by chemical vapor deposition (CVD). An activation energy of 0.58 eV and a capture cross section between 1×10−14 cm2 and 3×10−14 cm2 was determined for this level. Even though the D-center in these diodes is thought to arise from unintended trace contamination, we observed within the same diode a factor of twenty greater density of this level in the n-type layer than in the p-type layer, which is explained by a recently proposed site competition model for impurity doping during 6H-SiC CVD growth.