Mid-infrared emitter via heterogeneous integration of black phosphorus on GaN micro-LEDs

The development of pixelated and CMOS-compatible mid-infrared (MIR) light sources is of great interest for high-density emitter arrays and on-chip MIR imaging. However, emerging MIR emitters based on two-dimensional materials are constrained by challenging electrical contacts and random emission footprints. Here, we demonstrate a hybrid MIR emission architecture by heterogeneously integrating black phosphorus (BP) flakes onto GaN-based Micro-LEDs. By utilizing the Micro-LED as a light-pumping platform, the device achieves room-temperature MIR emission at ∼3.62 μm with strong linear dichroism. Temperature-dependent electroluminescence characterizations from 300 K to 80 K reveal a synergetic competition mechanism between the injection current of the Micro-LED and the quantum efficiency of the BP layer. The device exhibits a peak external quantum efficiency of ∼0.028% at 300 K. The pre-patterned Micro-LED mesa defines the nominal lateral pumping area of each BP/Micro-LED emitter unit, providing a potential route toward future pixelated MIR arrays compatible with silicon photonics.