Development of a Scalable High-Power LED-Based Inspection Platform for Correlative Photoluminescence and Electroluminescence Mapping of LED Chips.

In this work, we developed a measurement platform that employs high-power LEDs as excitation sources in conjunction with a charge-coupled device to perform spatially resolved photoluminescence (PL) and electroluminescence (EL) mapping of commercial LED chips. Two optical configurations (i.e., normal and oblique incidence) were designed to directly compare PL and EL distributions. Unlike conventional laser-based systems, high-power LEDs provide a cost-effective, compact, and scalable solution for PL mapping and provide a broad area of illumination, making them highly suitable for rapid chip-level inspection with strong potential for future wafer-scale scaling. The PL spectra obtained under high-power LED excitation exhibited strong correspondence with the EL spectra. Spatial mappings revealed key emission features, such as metallic contacts, defect-related spots, and surface contamination. The oblique-collection geometry yielded a more intense PL signal and clearer localized emission variations relative to the normal-collection geometry. These findings demonstrate that high-power LED-based PL mapping represents a practical and noninvasive alternative to EL, providing a reliable and scalable pathway for optical inspection of LED chips in both research and industrial applications.