2-D Carrier Lifetime Mapping in Flip-Chip Green Mini-LEDs by Time-Gated Electroluminescence Microscopy

A time-gated electroluminescence microscopy method is developed to map the 2-D carrier lifetime distribution in flip-chip green mini-LEDs with micrometer-scale resolution. An in-depth analysis of the fitting model for the proposed method shows general agreement with the classical bi-exponential model. Pixel-level bi-exponential analysis yields fast and slow decay components, based on which an internal quantum efficiency (IQE) indicator is constructed and fused with the average lifetime image, enabling device classification into high-performance, trap-localized, and defect-cluster regions. The characteristics of the three regions are associated with underlying physical mechanisms and can be well explained. Correlating these microscopic characteristics with fabrication parameters provides methodological guidelines for low-damage etching, optimized passivation, improved dopant uniformity, and enhanced current injection, offering a comprehensive analysis framework for performance enhancement and reliability improvement of miniaturized LEDs.