Valence Band Splittings of 15R SiC Measured using Wavelength Modulated Absorption Spectroscopy

摘要

15R SiC has significant advantages over 4H and 6H SiC for certain device applications. We have measured the free exciton low temperature photoluminescence (LTPL) spectrum for E perpendicular c and the wavelength derivative of the absorption coefficient dalpha/dlambda of 15R SiC for both polarizations E perpendicular c and E || c using modulation absorption spectroscopy. We use the E perpendicular c intrinsic 2 K photoluminescence spectrum to make assignments to features in the E perpendicular c absorption derivative spectrum. We obtain 7.15+-0.25 meV for the spin orbit splitting, in agreement with previous work, but with improved precision. The determination of the crystal field splitting is more challenging. We argue for a value of about 51 meV. This value is in good agreement with recent calculations.