AlGaN-based deep ultraviolet light-emitting diodes grown on nano-patterned sapphire substrates with significant improvement in internal quantum efficiency

We report high-performance AlGaN-based deep ultraviolet light-emitting diodes grown on nano-patterned sapphire substrates (NPSS) using metal−organic chemical vapor deposition. By nanoscale epitaxial lateral overgrowth on NPSS, 4-μm AlN buffer layer has shown strain relaxation and a coalescence thickness of only 2.5μm. The full widths at half-maximum of X-ray diffraction (002) and (102) ω-scan rocking curves of AlN on NPSS are only 69.4 and 319.1arcsec. The threading dislocation density in AlGaN-based multi-quantum wells, which are grown on this AlN/NPSS template with a light-emitting wavelength at 283nm at room temperature, is reduced by 33% compared with that on flat sapphire substrate indicated by atomic force microscopy measurements, and the internal quantum efficiency increases from 30% to 43% revealed by temperature-dependent photoluminescent measurement. •High-performance AlGaN-based deep ultraviolet light-emitting diodes were grown on nano-patterned sapphire substrates (NPSS).•A 4-μm AlN buffer layer shows strain relaxation and a coalescence thickness of only 2.5μm.•Both AlN and AlGaN-based multi-quantum wells on NPSS show decreased threading dislocations, strain relaxation and better material qualities compared with those on flat sapphire substrate.•The internal quantum efficiency of AlGaN-based multi-quantum wells grown on NPSS increases from 30% to 43%, compared with that on flat sapphire substrate.