Single-chip 260 nm pseudomorphic ultraviolet light emitting diode emitting over 200 mW output power

Ultraviolet-C (UVC) disinfection is considered environmentally friendly since it does not create any chemical load on the environment and does not generate any hazardous byproducts. Mercury lamps (which are essentially fluorescent lights without the phosphors) are currently used by municipalities to generate UVC but mercury lamps are not an attractive solution for low volumes or non-continuous use due to high power consumption, fragility and disposal issues. UVC LEDs would be an attractive alternative but, unlike visible LEDs, the current generation of UVC LEDs, fabricated from nitride semiconductors grown on foreign substrates, is rather inefficient with relatively poor lifetimes. Crystal IS is developing UVC LEDs to solve these issues by utilizing very high quality pseudomorphic layers of Al_xGa_1-xN grown on native AlN substrates prepared from high quality, bulk crystals. These layers are fabricated into mid-ultraviolet light emitting diodes (referred to as pseudomorphic ultraviolet light emitting diodes or PUVLEDs) with peak wavelengths in the range of 240-275 nm. The low threading dislocation density in the active region (<;10⁵ cm^-2) enables the achievement of high internal quantum efficiency while maintain high current injection efficiency. Packaged devices with powers ranging from 0.5 to 5mW at 100mA input current are being fabricated in this wavelength range which is attractive for instrumentation applications. Prior to measurements, the devices were burned in for 48 hours to provide stable output power with lifetimes in excess of 10,000 hours when run at 100mA cw.