Improved Light Output of AlGaInP-Based Micro-Light Emitting Diode Using Distributed Bragg Reflector

Abstract

We investigated how the performance and reliability of AlGaInP-based red (620 nm) micro-light-emitting diodes (micro-LEDs) (25 x 17 mu m(2)) were influenced by the use of n-AlInP ohmic layer and distributed Bragg reflector (DBR). The AlGaAs-based DBR showed reflectivity of 94.9% at 622 nm with a 14 nm-stopband width. The micro-LEDs with n-GaAs gave slightly lower forward voltages by 0.013 - 0.021 V than those with n-Al0.5In0.5P/n-Al0.6Ga0.4As and n-A(l0.5)In(0.5)P/DBR. However, the micro-LEDs with n-Al0.5In0.5P/n-Al0.6Ga0.4As and n-Al0.5In0.5P/DBR gave 61% and 125% higher light output power at 20 mu A compared with that with n-GaAs. It was shown that after annealing at 120 degrees C for 2,000 h, the forward voltage and the light output power at 4.7 A/cm(2) of the micro-LEDs with n-Al0.5In0.5P/DBR were degraded by 0.09% and 6.33%, respectively, with reference to those before annealing.