Enhancing the Output Power of 308 nm UVB-LED by Strain Modulation Through Mg Incorporation in AlN

Ultraviolet light-emitting-diodes (UV-LEDs) encounter substantial challenges in enhancing output power due to significant lattice mismatches between the n-type contact layer and underlying AlN template. In this study, a strain-modulated UVB-LED is proposed through Mg incorporation on top of the AlN layer. Mg incorporation effectively expands the lattice constant of the top layer of AlN, reducing the lattice mismatch between AlN and AlGaN. The density of the screw-type dislocations in the n-AlGaN layer was reduced from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.41\times 10^{8}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9.22\times 10 ^{7}$ </tex-math></inline-formula>cm−2. The fabricated 308 nm-emission UVB-LED with Mg incorporation in AlN exhibits 13.6% higher light output power and reduced operation voltage compared to LED without Mg incorporation. This work provides a promising solution towards the development of high-efficiency UVB light emitters.