Improved AlN buffer layer technologies for UV-LEDs

Growth of AlGaN based structure on AlN buffers grown directly on sapphire is reported. Such buffers show excellent morphology but a high density of edge dislocations. Growth of GaN on such layers allows dislocation bending and annihilation. Improved UV emission compared to structures grown on GaN prepared conventionally has been observed. Using AlGaN on ALN gives significantly less dislocation reduction, but efficient 340 nm LEDs have been fabricated on this template. For further dislocation reduction overgrowth on a porous AlN film has been developed, leading to much improved room temperature luminescence, indicating the technology's potential for UV-LED device fabrication.