InAlN underlayer for near ultraviolet InGaN based light emitting diodes

Abstract

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 ∼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.