Hall effect investigations of 4H–SiC epitaxial layers grown on semi-insulating and conducting substrates

Nitrogen- and aluminum-doped 4H silicon carbide epitaxial layers were grown simultaneously on semi-insulating and conducting substrates. The layers were investigated by conventional van der Pauw Hall effect measurements and for comparison also with secondary ion mass spectrometry and capacitance voltage measurements. It was found, that the carrier concentration in the layers grown on conducting substrates were overestimated by the Hall effect measurement, which leads to an underestimation of the ionization energy of the main dopant, as compared to the layer grown on semi-insulating substrates. The difference can be explained by a two-layer Hall effect model.