752-MHz Modulation Bandwidth of High-Speed Blue Micro Light-Emitting Diodes

Abstract

In this paper, the optical frequency response of gallium nitride-based blue micro-LEDs with different quantum well numbers in the active region is presented. Single quantum well (SQW) blue micro-LEDs have about 1.6 times higher modulation bandwidth ( $f_{-3\,\text {dB}}$ ) by comparison with triple quantum well blue micro-LEDs. The larger bandwidth enhancement of the SQW micro-LEDs can be attributed to more carriers stored in a quantum well leading to higher recombination rate and lower recombination lifetime. The high $f_{-3\,\text {dB}}$ up to 752 MHz is demonstrated in the SQW micro-LED with a light-emitting area of $10\,\,\mu \text {m} \times 10\,\,\mu \text{m}$ . It suggests that micro-LEDs designed with fewer quantum well numbers may have the potential for the application of visible light communication (VLC) technology.