Room-Temperature Phonon Replica in Band-to-Band Transition of 6H-SiC Analyzed Using Transmission Spectrums

Room-temperature phonon replicas in the band-to-band transition of 6H-SiC were analyzed using transmission spectrums (TSs). By fitting the experimental data with theoretical equations, the energies of two turning points were determined to be Eg+Ep and Eg-Ep. the Eg values were about 2.976 eV for low-resistivity (LR) 6H-SiC and 2.970 eV for semi-insulating (SI) 6H-SiC, while the Ep values were about 56 meV for the former and 63 meV for the latter, which were consistent with the values extracted by the conventional method. The difference between the band gap energies of the LR and SI 6H-SiC samples was due to the Moss–Burstein effect. At room temperature, phonons participating in the band-to-band transition of 6H-SiC were dominated by longitudinal acoustic (LA) phonons with energies of about 56–63 meV.