This study fabricated and analyzed AlGaInP-based red micro-light-emitting diodes (LEDs) ranging from 2 to 15 μm in size. To collect photons from a single micro-LED at this scale, a solar cell chip near the micro-LEDs was used. Quantum efficiency decreased at a faster rate than that predicted by the standard ABC model under high currents, and a leakage current component was added to fully describe this phenomenon. The modified model can be used to extract valuable information regarding the micro-LEDs, such as the Shockley-Read-Hall coefficient. A size dependency analysis revealed that the bulk Shockley-Read-Hall coefficient and surface recombination velocity of the micro-LEDs were 6.81 × 107 1/sec and 5.99 × 104 cm/sec, respectively. Further analysis of the size-dependent recombination effect can help us solve the side wall problem and maximize the light output of AlGaInP-based micro-LEDs for ultrahigh-resolution displays.