(AlGaIn)N ultraviolet LED chips and their use in tri-phosphor luminescence conversion white LEDs

We report on the development of (AlGaIn)N quantum well LEDs covering the 380 to 430 nm wavelength range, which serve as the primary light source for tri-phosphor luminescence conversion white LEDs. Epitaxial layer growth was performed by low-pressure metal-organic chemical vapor deposition on sapphire substrates. Mesa LEDs were fabricated and either mounted in standard epoxy-based 5 mm radial LED packages or flip-chip bonded on ceramic submounts. Then, LED-chips with peak wavelengths matching the absorption spectrum of an appropriately chosen inorganic tri-phosphor blend, were used for the fabrication of single-chip tri-color luminescence conversion white LEDs. These devices allowed us to demonstrate the feasibility of the above concept for improved color rendering and tunability.