The Conduction Bands in 6H and 15R Silicon Carbide. I. Hall Effect and Infra-Red Faraday Rotation Measurements

摘要

Measurements of infra-red Faraday rotation and Hall effect were made in a number of specimens belonging to the 6H and 15R polytypes of silicon carbide. Within experimental error the Hall coefficient in these samples was found to be isotropic and it is concluded that the conduction band extrema in both polytypes are most probably located on the symmetry axis. For this model the Faraday rotation results give the effective mass appropriate to directions perpendicular to the axis of symmetry as 0.25 plus or minus 0.02 m sub o in the 6H polytype and 0.28 plus or minus 0.02 m sub o in the 15R polytype. Considerable care was required to ensure that the specimens used were uniform in carrier concentration and free from serious crystallographic faults; the precautions taken to meet these requirements and in particular the avoidance of one frequently occurring crystallographic imperfection are described in some detail. All the measurements were made at room temperature. (Author)