Quantitative Cathodoluminescence Mapping of External Radiative Efficiency in LEDs

This study introduces a quantitative cathodoluminescence (CL) measurement technique using an integrating sphere inside a scanning electron microscope (SEM). This technique allows one to access the external radiative efficiency (ERE), i.e., the product of radiative recombination and light extraction efficiencies. This contactless method was applied to map the efficiency of processed blue-emitting microlight-emitting diodes (LEDs) and deep UV-emitting nanowire-based heterostructures, demonstrating its versatility across semiconductor materials. Because the technique requires no preprocessing, it enables rapid, large-scale control of the homogeneity of emission yield right following epitaxy. Capable of operating across a wide field of view from the visible to the deep-UV range, this approach provides a nondestructive pathway for characterizing efficiencies of LEDs and solid-state emitters.