We report on InAlN underlayer (UL) to improve the efficiency of near ultraviolet (NUV) light emitting diodes (LEDs). While InGaN UL is commonly used in high-efficiency blue LEDs it may absorb light for shorter wavelengths. InAlN lattice-matched to GaN exhibits a bandgap of 4.6 eV. This allows alleviating absorption issues in NUV LEDs. We demonstrate that the internal quantum efficiency of 405 nm single InGaN/GaN quantum well LEDs with InAlN UL is similar to 70% compared to less than 10% for LEDs without UL. Excellent I-V characteristics are achieved thanks to polarization charge screening with high doping level at the InAlN/GaN interface. (C) 2019 The Japan Society of Applied Physics