Temperature dependence of optical absorption coefficient of 4H- and 6H-SiC from room temperature to 300 °C
Optical absorption coefficients of 4H- and 6H-SiC were measured at cutoff wavelengths from a value of 0 to 400-500 cm-1 at various temperatures that is from room temperature to 300 °C. The redshift of the absorption edge with increasing temperature was observed. It is caused by a decrease in bandgap energy and a change in phonon occupation with increasing temperature. By considering TA-, LA-, and TO-mode phonon-assisted indirect transitions, the measured data are well fitted using a theoretical model. The obtained parameters are reported.