GaN-based Micro-LED has become a research hotspot as a novel display technology due to its numerous unique advantages. Especially in augmented reality and smart glasses applications, Micro-LED display chip with high transparency possesses unparalleled opportunities. In this work, GaN-based transparent single-color Micro-LED display chip based on double-side polished sapphire substrate was designed with a single pixel size of $20\,\,\mu \text{m}\times 20\,\,\mu \text{m}$ , and a resolution of 254 pixel per inch (PPI). The transparency reaches 80% among the whole display area ~ 0.18 inch, and the luminance of display chip can reach up to 25000 nits. It demonstrates a broad application prospects in augmented reality, smart glasses, and etc., providing promising vista for the development of “Metaverse” in the future.

We have investigated an Al modulation epitaxy (AME) method to obtain step-flow growth of Al droplet free AlN layers by plasma assisted molecular beam epitaxy (MBE). At the usual growth temperature of (Al)GaN/AlN heterostructures, Al atom migration and desorption rate are very low and consequently it is very difficult to avoid the formation of Al droplets on AlN growth front by conventional MBE growth method. By adopting the AME growth method, such a difficulty has been effectively overcome and step flow growth mode of AlN has been clearly observed. By optimizing the AME growth time sequence, namely, AlN growth time and N radical beam treatment time, Al droplet free AlN layers with step flow growth characteristics have been obtained, with atomic flat surfaces and an average atomic step width of ∼118 nm at 970 °C–1000 °C, which is still suitable to grow (Al)GaN/AlN heterostructures by MBE.