UD-3 defect in 4H, 6H, and 15R SiC: Electronic structure and phonon coupling - art. no. 115204

摘要

The UD-3 photoluminescence (PL) spectrum is observed in high-resistive or semi-insulating bulk 4H, 6H, and 15R SiC. It consists of one no-phonon (NP) line in 4H and 6H SiC and two NP lines in 15R SiC. The line positions are 1.3555 eV in 4H SiC, 1.3440 eV in 6H SiC and 1.3474 eV (UD-3(L)) and 1.3510 eV (UD-3(H)) in 15R SiC. In PL excitation experiments, an additional set of four lines (UD-3(I)-UD-3(IV)) is observed in all three polytypes. The symmetry of the ground state and the excited states involved in these transitions is determined from Zeeman and polarization experiments. The NP line is accompanied by a broad phonon assisted side band. In addition, three sharp transitions UD-3(a), UD-3(b), and UD-3(c) and three broader features have been observed. These are assigned to local phonons. [References: 36]