Optically revealing single electrically active dislocations in GaN-on-Si via one-to-one structure–electronic correlation

Despite the high density of threading dislocations in heteroepitaxial GaN (>109 cm−2), only a small subset with deep-level states (DLS-TDs) critically degrade the performance of power devices by serving as carrier trapping and re-emission centers. However, the fundamental nature of these nanoscale extended defects remains controversial and no nondestructive technique currently enables their selective detection. Here, we demonstrate a purely optical technique capable of identifying electrically active DLS-TDs at the single-dislocation level in GaN-on-Si structures. By preparing TDs with partially etched configurations, we uncover site-specific correlations between surface etch-pit morphology and subsurface electronic transitions of dislocation lines. This one-to-one analysis reveals that most open-core threading screw dislocations (TSDs) are electrically benign, while a small fraction of full-core TSDs and mixed-type TDs exhibit ultrabroad, multi-peaked deep-state emissions, indicating both optical and electrical activity. Our approach provides new insights into the defect nature of DLS-TDs and offers a contactless method for material-level TD inspection.