Effects of electron mass anisotropy on Hall factors in 6H-SiC

The room temperature Hall factors in 6H-SiC have been measured under different magnetic fields. It is found that the Hall coefficient RH increases with magnetic field, implying a Hall factor of less than one at zero magnetic field. This behavior has been accounted for by a model based on electron mass anisotropy in 6H-SiC. The Hall factor results show that in 6H-SiC the mass along the c direction is a factor of 5 larger than that in the transverse direction and that the electron-phonon scattering time is aobut 1 ps at room temperature, which is consistent with a recent optically detected resonance spectroscopy measurement. Our results indicate that the Hall measurement can be utilized as an effective and simple method for studying scattering mechanisms as well as for determining anisotropic transport properties in SiC and that a correction of the Hall factor is necessary in order to determine the carrier concentration and mobility accurately.