Brightness Improvement and limited Forward Voltage of the AlGaInP MQW LED with Wet-Oxidation by Taguchi Method

Abstract

To increase the external quantum efficiency of LED while limiting its forward voltage (Vf), we prepared both (AlxGa1–x)0.5In0.5P LED and buried oxides through selective wet oxidation of the AlAs layers of AlAs/GaAs distributed Bragg reflectors (DBRs). The wet oxidation process forms a stable AlxO material that acts as an insulation layer that affects both the carrier and optical confinements. The stable AlxO material that formed confined the transport region of injection carriers effectively and strongly decreased the chance of the carrier being trapped within the surface layer. To determine the trade-off conditions for LED oxidation, we used the Taguchi method which is a robust technique that is often used to analyze the significant trends that occur under a set of oxidation condition. In this study we uses an L9orthogonal array to measure the effects that a series of factors have upon the maximum brightness performance of the LED in an effort to limit the values of Vf. Relative to the as-grown LED, the oxidized LED that was treated under the trade-off wet-oxidation conditions displayed a sharply enhance the brightness (62.4% increase) in conjunction with only a slightly increased value of Vf(only a 24.5% increase).