Nanoscale investigation of extended defects in wide-bandgap semiconductors by exploiting phonon-resonant near-field interaction

We show how extended defects in wide bandgap semiconductors manifest in the nanoscale infrared phonon response probed by scattering-type scanning near-field optical microscopy (s-SNOM). We correlate the s-SNOM response of various defects in 4H-SiC with UV-photoluminescence, secondary electron and electron channeling contrast imaging, and transmission electron microscopy. We identify evidence of step-bunching, recombination-induced stacking faults, and threading screw dislocations, and also demonstrate the interaction of surface phonon polaritons with extended defects. Our s-SNOM results help to advance material growth efforts for electronic, photonic, phononic, and quantum optical applications.