Optical Access to the Electronic Nature of Device-Relevant Dislocations in High-Purity Semi-Insulating SiC

High-purity semi-insulating silicon carbide (HPSI-SiC) is a high-end substrate for power devices. However, both electrical and optical characterization of threading dislocations (TDs) remains challenging because of its low free-carrier concentration and abundant compensating deep-level defects. Here, we develop an optical technique for the selective identification and electronic characterization of device-relevant TDs with continuously distributed deep-level states. By employing partially etched TDs, TD types can be resolved through laser backscattering from etch-pit morphology, while their electronic activity is assessed via deep-level photoluminescence (PL) from the underlying dislocation lines. Statistical one-to-one structural-electronic correlation reveals that only a small fraction of pure screw-type TDs exhibits broadband deep-level emission, which is attributed to inherent dislocation-core states. These deep-level TDs may potentially form leakage-current pathways through trap-assisted mechanisms. Our work demonstrates a nondestructive PL-active approach for optically identifying deep-level TDs in HPSI-SiC.