Efficiency Improvement of 630nm AlGaInP Light-Emitting Diodes based on AlGaAs Bottom Window

Metal organic chemical vapor deposition (MOCVD) based aluminum gallium arsenide (AlGaAs) used as the bottom window (BW), which was inserted between the light-emitting diode (LED) structure and the absorbing substrate, has been proposed to improve the extraction efficiency of 630nm AlGaInP LEDs. In an AlGaInP LED with this AlGaAs BW, enhanced light extraction efficiency was observed, as some of the light emitted from the active region to the absorbing substrate could pass out of the LED through the BW. In addition, it was found that a output power of 8mW was obtained from an AlGaInP LED with both a BW and a distribution Bragg reflector (DBR), a nearly two fold improvement of over 4.2mW that was obtained from a conventional one at an injection current of 80 mA.