Using the Taguchi method to improve the brightness of AlGaInP MQW LED by wet oxidation

To increase the external quantum efficiency of a light-emitting diode (LED) while limiting its forward voltage (V_f), we prepared both (Al _xGa_1-x)_0.5In_0.5P LED and buried oxides through selective wet oxidation of the AlAs layers of AlAs-GaAs distributed Bragg reflectors. The wet oxidation process forms a stable Al _xO material that acts as an insulation layer and affects both the carrier and optical confinements. To determine the tradeoff conditions for LED oxidation, we used the Taguchi method which is a robust technique that is often used to analyze significant trends that occur under a set of oxidation conditions. In this study, we used an L₉ orthogonal 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 V_f. Relative to the as-grown LED, the oxidized LED that had been treated under the tradeoff wet-oxidation conditions displayed a sharply enhanced brightness (62.4% increase) in conjunction with only a slightly increased value of V_f (only a 24.5% increase).