Light Emitting Diodes for the Ultraviolet Spectral Region

The main goal of this project is the development of ultraviolet light emitting diodes (UV LED) for the wavelength range from 400 nm to fewer than 250 nm. The research work is motivated by numerous applications, which can be realized with UV LED devices. Such as

• Purification of drinking water, waste water, and process water
• Sterilization of food
• Medical applications (e.g. dermatology, light therapy)
• Bio analytics (e.g. fluorescent microscopy)
• Sensor technology (e.g. measurement of nitrogen oxides, blankophor measurements)
• Surface polymerization (e.g. printing inks, lacquers, epoxy resins)
• Light sources for free-space data communication

The required emission wavelengths depend strongly on the application and will therefore vary over a wide spectral range. One of the challenges is it to realize efficient LEDs within the entire UVA and UVB range as well as parts of the UVC range. So far the research activities have concentrated on the development of LEDs in the near UV. First 375 nm LEDs were demonstrated with an output power of more than 4 mW (measured on-wafer). The current research activities concern primarily the epitaxy of InAlGaN heterostructures and LED chip development, in order to gradually move towards shorter wavelengths UV LEDs.