We report the electrical and optical characteristics of an AlGaN/AlGaN quantumwell ultraviolet (UV) light-emitting diode (LED) grown on sapphire by metalorganic chemical vapor deposition, The devices operating under room-temperature DC excitation exhibit a peak emission wavelength at 341 nm with a narrow line width of Deltalambda = 10 nm. We also report a ternary AlGaN UV LED grown on sapphire with peak wavelength emission at 302 nm. The device utilized a double heterostructure. along with a Mg-doped AlGaN AlGaN superlattice structure Lis a p-cladding layer. The emission peak exhibits a narrow line width of Deltalambda. = 10 nm. (C) 2002 Elsevier Science B.V. All rights reserved.