ABSTRACT
Abstract. AlGaN-based ultraviolet light emitting diodes (LED) are characterized. The devices consist of an Alo.00Gao.94N (2 nm) / Alo.12Gao.88N single quantum well active layer sandwiched by Alo.3Gao.7N carrier blocking layers and cladding layers of an Alo.i6Gao.84N (1.5 nm)/Al0.2Gao.8N (1.5 nm) short-period alloy superlattice grown on bulk GaN substrate. Efficient conversion to UV light is confirmed, which indicates a high-quality active layer, effective suppression of carrier overflow, and transparency of conductive cladding layers. Radiative recombination dominantly occurs in the quantum well at injection current density lower than 0.25 kA/cm2. Further dense injection leads to enhancement of the radiative recombination in the barrier layer. This clarifies the importance of the design of the active layer for highpower application. 1
Aluminium gallium nitride (AlGaN) alloy is optically direct band gap material and it covers a wide wavelength range of 200-360 nm within ultraviolet (UV) range. Therefore, AlGaN-based light emitting diodes (LEDs) are expected to be the next-generation of ultraviolet (UV) light sources. Such a semiconductor UV light source will replace fluorescent bulbs for lighting, electroluminescence panels and cathode tubes for displays, and gas tubes for spectroscopic excitation applications, such as used in medicine.
