High-efficiency resonant-cavity LEDs emitting at 650 nm

We fabricated resonant-cavity light-emitting diodes (LEDs) emitting at 650 nm. Compressively strained GaInP quantum wells were used as an active layer embedded between AlGaAs-AlAs Bragg mirrors. The Bragg mirrors formed a one-wavelength optical resonator. Two devices with different light-emitting areas were compared: 1) a large area chip (300 μm×300 μm) with a conventional LED contact and 2) a small area chip with an 80-μm light opening with an annular contact. Large devices are more suitable for high output power whereas the smaller devices might be useful for data transmission e.g., via plastic optical fibers. For epoxy-encapsulated large area devices, we achieved a maximum wall-plug efficiency of 10.2% and maximum output power of 12.2 mW at 100 mA. The small area LEDs yielded 2.9 mW at 20 mA and a maximum wall-plug efficiency of 9.5%