Nondestructive detection and identification of electrically active threading dislocations in n+-SiC substrates

Abstract

Threading dislocations (TDs) are the most abundant extended defects in highly n-doped SiC (n⁺-SiC) substrates. Notably, only a small subset, those hosting deep states (DS-TDs), can potentially impact device operation. However, selective detection of such electrically active DS-TDs using conventional photoluminescence (PL) techniques remains challenging due to universal PL quenching across all defects. Here, we develop confocal subsurface defect-PL spectro-microscopy to selectively detect screw-component DS-TDs (DS-STDs) in n⁺-SiC substrates. By directly photoionizing the occupied deep states, DS-STD-specific emissions can be activated. Such inherent deep-level emissions of dislocation lines, combined with external surface-state emissions at the etch pits, enable the reconstruction of 3D images with high contrast for the partially etched DS-STDs. This approach overcomes the limitations of conventional PL and paves the way for non-destructive, in-line inspection of electrically active dislocations even in highly doped SiC substrates.