Investigation of Forward Voltage Uniformity in Monolithic Light-Emitting Diode Arrays

This letter reports the design and fabrication of optimized electrode structures for matrix addressable monolithic light-emitting diode arrays. The variation of forward voltages of LED pixels in the same row are greatly reduced from 2.62 V (81.9%) to 0.02 V (0.6%) in an 8×8 LED array. The LED arrays are designed with 8×8 square pixels, 500×500 μm2with a 50-μm wide gap in between. A 24×24 large-scale blue LED panel is demonstrated with 0.06 V (1.8%) forward voltage variation by integrating nine LED array modules on a 2.2-cm diagonal silicon-based substrate. With a similar concept, a 30×30 green LED micro-display with scaled pixel pitch shows excellent display uniformity.