Nitrogen-polar GaN quantum dots with tunable emission in the ultraviolet-A, B, and C bands

In this study, we report on the molecular beam epitaxy and characterization of nitrogen-polar (N-polar) GaN quantum dots (QDs) grown on SiC substrates. By varying the growth conditions, the emission wavelengths of GaN QDs can be controllably tuned across a large part of the ultraviolet-A, B, and C bands. For N-polar QDs emitting at 243 nm, we measured an internal quantum efficiency (IQE) of 86.4% at room temperature, with predominantly transverse-electric (TE) polarized emission. Such N-polar GaN QDs offer a promising path for achieving high-efficiency mid- and deep-ultraviolet optoelectronics, including light-emitting diodes and lasers.