Improvement in Modulation Bandwidth of Micro-LED Arrays Based on Low-Temperature-Interlayer Approach

To promote the modulation bandwidth of GaN-based blue micro-light emitting diodes ( $\mu $ -LEDs) for visible light communication, the multiple quantum well active region has been improved via approaches based on low-temperature (LT) GaN insertion layer in barriers. $\mu $ -LED arrays with 10 $\times $ 10 pixels have been fabricated. The device using LT-GaN interlayer has an output power of 2.14 mW and a modulation bandwidth of 220 MHz, with an enhancement factor of 2.5 and 1.7, respectively, as compared with the device without LT-GaN interlayer. It is believed that these improvements are a result of the suppression of strain-related quantum-confined Stark effect and defects/dislocations by LT-GaN interlayer based optimization. The LT-GaN interlayer not only facilitates a tensile strain in barriers, making it more lattice-compatible with InGaN well to reduce the strain there, but also has an effect on blocking the propagation of threading dislocation into upper layers. Our work provides an effective approach to enhance the modulation bandwidth of III-nitride $\mu $ -LEDs using LT interlayer.