Properties of 6H–SiC crystals grown by hydrogen-assisted physical vapor transport

Effects of hydrogen addition to the growth ambient during physical vapor transport (PVT) growth of 6H–SiC were investigated using secondary ion mass spectrometry, deep level transient spectroscopy, and Hall effect measurement. The background nitrogen concentration and the free electron density decrease with increasing hydrogen content. The formation of electron traps (activation energies of 0.4 eV, 0.6 eV, 0.7 eV, 0.9 eV, and 1 eV) was also strongly suppressed. The above results are interpreted as a consequence of hydrocarbon formation produced by the reaction of hydrogen with the SiC source and the graphite parts of the furnace. This leads to more congruent evaporation of SiC and the shift of the gas phase and the SiC deposit stoichiometry due to less Si-rich conditions than in standard PVT growth.