Modulation bandwidth improvement of GaN-based green micro-LEDs array by polarization-induced p-type doping

Abstract

As one of the most promising candidates for signal carrier sources in visible light communication, GaN-based green micro-light emitting diodes ( μ-LEDs) exhibit a limited modulation bandwidth. In this work, we propose an approach to accelerate carrier recombination rate in green μ-LEDs and, thus, improve the modulation bandwidth by enhancing p-type conductivity to allow more efficient hole injection into an active region. The polarization-induced p-type doping with graded AlGaN enhances the p-type layer conductivity to 2.5 × 10−2 S/m, which is about 4 times in magnitude higher than that of the conventional p-type GaN layer (0.6 × 10−2 S/m). 16 × 16 green μ-LEDs arrays using such graded p-AlGaN exhibit a light output power of 4.4 mW and a modulation bandwidth of 130 MHz, both showing an improvement of about 45% as compared with the ones using a pure p-GaN layer. The polarization-induced p-type doping in graded AlGaN would accelerate the application of GaN-based μ-LEDs in visible light communication.