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GaN nanorods (NRds) with axial InGaN/GaN MQWs insertions are synthesized by an original cost-effective and large-scale nanoimprint-lithography process from an InGaN/GaN MQWs layer grown on c-sapphire substrates. By design, such NRds exhibit a single emission due to the c-axis MQWs. A systematic study of the emission of the NRds by time-resolved luminescence (TR-PL) and power dependence PL shows a diameter-controlled luminescence without significant degradation of the recombination rate thanks to the diameter-controlled strain tuning and QSCE. A blueshift up to 0.26 eV from 2.28 to 2.54 eV (543 nm to 488 nm) is observed for 3.2 nm thick InGaN/GaN QWs with an In composition of 19% when the NRds radius is reduced from 650 to 80 nm. The results are consistent with a 1-D based strain relaxation model. By combining state of the art knowledge of c-axis growth and the strong strain relieving capability of NRds, this process enables multiple and independent single-color emission from a single uniform InGaN/GaN MQWs layer in a single patterning step, then solving color mixing issue in InGaN based nanorods LED devices. [ABSTRACT FROM AUTHOR]

An approach to simultaneously grow independent core‐shell structures emitting at different wavelengths by selective area epitaxy is presented. By using seeds of different sizes, the monolithic integration of various GaN crystals including elongated nano‐rods (NRs), micro‐platelets (MPs), and a range of pyramid‐like structures are demonstrated. Dominant non‐polar sidewalls cover more than 75% of the surface area of the NRs, while the polar top facet are about 80% of the total surface of the MPs. InGaN/GaN quantum wells (QWs) deposited on these structures exhibit independent and well‐separated emissions in the green–blue and orange–red ranges, respectively. The pyramid‐like structures at intermediate seed sizes are more complex with semi‐polar facets nearly totaling 60% of the total surface area, resulting in yellow luminescence strongly broadened by the nearby facets contributions. These results suggest the total surface area of each facets and the resulting optical properties of the crystals can be tailored by adjusting the size of the seeds. However, further improvements are required to locally enhance the vertical, pyramidal, and lateral growth of the GaN cores and increase the spectral purity of the different QWs. The approach presented is of interest to design multi‐wavelength devices which requires independent subpixels of high color purity. An approach to simultaneously grow independent core‐shell structures emitting at different wavelengths by selective area epitaxy is presented. By using seeds of different sizes, the monolithic integration of various GaN crystals including elongated nano‐rods, micro‐platelets, and pyramid‐like structures are demonstrated. InGaN/GaN quantum wells deposited on these structures exhibit independent and well‐separated emissions in the green–blue and orange–red ranges, respectively. [ABSTRACT FROM AUTHOR]