Development and Fabrication of AlGaInP-Based Flip-Chip Micro-LEDs

The fabrication of AlGaInP-based flip-chip micro light-emitting-diodes (LED; emitting area: 4.5 mil x 5 mil) with horizontal electrodes is reported in this paper. The thickness of the epitaxial layer of the thin LED structure was reduced to 50% of that of the traditional thick LED, whereas carrier concentration in the n-type GaAs contact layer was increased to 5 x 10(18) cm(-3) to meet the Ohmic contact requirement. At a current injection of 5 mA, the thin LED exhibited a forward voltage, output power, and external quantum efficiency of 1.8 V, 1.9 mW, and 19%, respectively. The optoelectronic performance of the thin LED was as good as that of the traditional thick red LED. The technique proposed by this paper can be used to integrate AlGaInP-based LEDs with nitride LEDs for full-color display applications.