Monolithic Light Reflector-Nanowire Light Emitting Diodes

The development of small size, ultracompact photonic devices is required for a wide range of applications, such as next-generation automobile displays, micro-light-emitting diode (µ-LED) TVs, smart phones and watches, virtual reality, and augmented reality. Here, for the first time, a new approach is reported to dramatically reduce the size of photonic device chips by using a monolithic light reflector-nanowire LED system. Moreover, the vertical cavity nanowire structure for the surface-lighting emission is developed by selective area epitaxy that can precisely control the gaps and diameters of the GaN nanowires. The light reflection is provided by high quality Al metal reflector which is directly deposited by molecular beam epitaxy (MBE) technique. The selective area growth shows uniform GaN heterostructure arrays with excellent crystal quality and desired aspect ratio. Furthermore, an advanced selective area etching process is introduced to fabricate Al mirrors between nanowire arrays. Significantly improved light efficiency is observed at ≈550 nm spectral wavelength from the monolithic Al light reflector-vertical surface emitting nanowire LED system. To break the “green gap” bottleneck in III-nitride photonics, the approach will open a new route toward monolithic, ultrasmall, electrically pumped nanoscale light emitters for next-generation photonic and electronic devices.