Giant enhancement of emission efficiency and light directivity by using hyperbolic metacavity on deep-ultraviolet AlGaN emitter

Despite the demands of growth, the development of deep-ultraviolet (UV) light-emitting diodes (LEDs) still suffers from the fundamental limits of material defects and the anisotropic optical property of AlGaN multiple quantum-wells (MQWs), resulting in an extremely low emission output. Here, we present a novel approach to address this issue by using a nanoscale hyperbolic metacavity on the deep-UV LED, where the resonant modes of metacavity are excited. An intense plasmon field is consequently feedback to the MQW. This strong resonant mode feedback allows the dipoles of MQW recombine directionally, thereby achieving enhancements of radiative emission rate by a factor of 160 and quantum efficiency by a factor of 3.5. It also shows the capability of metacavity in tailoring the direction of light emission, leading to a 520% increase in total emission intensity and 148% increase in emission extraction. A small divergence angle of 65 degrees of LEDs is therefore demonstrated. Our study clearly shows that the use of metacavity is a promising candidate for the highly-desired efficiency and directivity deep-UV applications, and the metacavity effect can be extended to other nanoscale devices, such as nanolaser, single photon source, nano-biosensor, and nano-antenna.