C-plane yellow–green InGaN micro-light-emitting diodes with 1.55 GHz modulation bandwidth for free-space visible-light communication

Yellow–green InGaN micro-light-emitting diodes (micro-LEDs) are attractive transmitters for visible-light communication, yet high-In-content quantum wells usually impose a trade-off among efficiency, optical power, and modulation speed. Here, we report c-plane single-quantum-well InGaN micro-LEDs emitting near 545 nm that combine milliwatt-level output at high-current density with gigahertz-class small-signal modulation. Devices with lateral sizes of 40 and 60 μm exhibit peak external quantum efficiencies (EQEs) of 5.36% and 5.35%, respectively, and retain EQEs of 2.84% and 2.83% at 1000 A cm−2. The 40 μm device reaches a maximum −3dB bandwidth of 1.55 GHz and maintains gigahertz-class bandwidth from a high operation temperature (300–375 K). We also demonstrate 2.0 Gbit/s free-space non-return-to-zero on–off keying transmission with an estimated bit-error rate below the 7% overhead hard-decision forward-error-correction limit. These results show that c-plane yellow–green InGaN micro-LEDs can provide compact, efficient, and thermally robust transmitters for high-speed free-space visible-light links.