Size effects of AlGaInP red vertical micro-LEDs on silicon substrate

To study the size effect of AlGaInP red micro-LEDs on the silicon substrate, we fabricated five AlGaInP red micro-LEDs with different pixel sizes (160 × 160, 80 × 80, 40 × 40, 20 × 20, and 10 × 10 µm2) and studied their electrical and optical properties. Smaller micro-LEDs have smaller leakage current and larger series resistance and can withstand higher current density without the current crowding effect. Due to the larger perimeter-to-area ratio of small-sized micro-LEDs, non-radiative recombination increases, which leads to a lower EQE. But smaller micro-LEDs can alleviate the problem of the high-current efficiency droop. In addition, because of a better heat dissipation under a high injection current, smaller micro-LEDs (>80 µm) have a smaller center wavelength shift. These experimental results provide important data for designing and fabricating red micro-LEDs with different pixel sizes for diverse future applications.