Optimization of P-electrode structures to enhance current spreading uniformity in micro-LEDs

In this study, we designed and fabricated parallel-connected green micro-LEDs with three different P-electrode configurations: rounded (Sample A), cross-shaped (Sample B), and circular (Sample C). We then systematically evaluated the impact of these electrode shapes on the devices' optoelectronic performance. The results show that the shape of the P-electrode significantly influences the optoelectronic performance of micro-LEDs. With a round mesa, Sample C exhibits the lowest operating voltage and the smallest dynamic resistance and achieves a peak external quantum efficiency (EQE) of 19.57%, which is 25.53% and 11.13% higher than that of Sample A (15.59%) and Sample B (17.61%), respectively. The analysis suggests that this improvement is mainly due to enhanced uniformity in current spreading and shorter current injection paths. COMSOL simulations, along with thermal resistance and surface temperature measurements, confirm that different P-electrode shapes affect the uniformity of current distribution in micro-LEDs, which in turn impacts the device's thermal performance. TracePro simulation results further demonstrated that circular P-electrodes optimize the light output of the device. We believe that this study provides a valuable reference for the design and fabrication of micro-LED chips.