Nanostructuring Multilayer Hyperbolic Metamaterials for Ultrafast and Bright Green InGaN Quantum Wells

Semiconductor quantum well (QW) light‐emitting diodes (LEDs) have limited temporal modulation bandwidth of a few hundred MHz due to the long carrier recombination lifetime. Material doping and structure engineering typically leads to incremental change in the carrier recombination rate, whereas the plasmonic‐based Purcell effect enables dramatic improvement for modulation frequency beyond the GHz limit. By stacking Ag‐Si multilayers, the resulting hyperbolic metamaterials (HMMs) have shown tunability in the plasmonic density of states for enhancing light emission at various wavelengths. Here, nanopatterned Ag‐Si multilayer HMMs are utilized for enhancing spontaneous carrier recombination rates in InGaN/GaN QWs. An enhancement of close to 160‐fold is achieved in the spontaneous recombination rate across a broadband of working wavelengths accompanied by over tenfold enhancement in the QW peak emission intensity, thanks to the outcoupling of dominating HMM modes. The integration of nanopatterned HMMs with InGaN QWs will lead to ultrafast and bright QW LEDs with a 3 dB modulation bandwidth beyond 100 GHz for applications in high‐speed optoelectronic devices, optical wireless communications, and light‐fidelity networks. Ultrafast and bright green InGaN quantum wells are demonstrated by utilizing nanopatterned Ag–Si multilayer hyperbolic metamaterials. The spontaneous recombination rate is enhanced by more than two orders of magnitude across a broadband of working wavelengths, with over tenfold enhancement in the peak emission intensity. The integration of hyperbolic metamaterials with quantum wells will lead to light‐emitting diodes beyond 100 GHz.