HALL-EFFECT AND INFRARED-ABSORPTION MEASUREMENTS ON NITROGEN DONORS IN 6H-SILICON CARBIDE

Hall effect and infrared absorption measurements of n-type silicon carbide of the 6H polytype are employed to investigate the energy position of the ground state and excited states of the nitrogen donor. A donor model is proposed that assigns four series of absorption lines to electronic transitions of three donor species residing at three inequivalent lattice sites (h,k1,k2). A valley-orbit splitting of 12.6 meV is determined for donors on the hexagonal site h. For 2p0, 2p+/-, 3p0, and 3p+/- excited states, the effective-mass approximation is found to hold within experimental errors assuming a transverse and longitudinal effective electron mass of m perpendicular-to = (0.24 +/- 0.01) m0 and m parallel-to = (0.34 +/- 0.02) m0, respectively.