Reducing the operating wavelength of laser diodes is desirable for a number of applications. Shorter wavelength enables the writing and reading of optical information at higher storage densities, as seen in the development of CD and DVD players over the past decade, in which the wavelength has decreased from infrared to blue. In addition, ultraviolet (UV) radiation at wavelengths below 390 nm can be used in fluorescence-based chemical and biological detection schemes.
The development of suitable materials that can be electrically driven and operated at ambient temperatures has, however, presented a significant challenge. Providing an addition to the small selection of wide-bandgap materials, such as diamond, that emit in the UV, and one that the wafer growers may find more attractive to work with, Fischer et al. present results on UV-emitting AlGaN-based light-emitting diodes. Their devices can operate at room temperature and provide around a milliwatt of 290-nm UV light when biased at around 10 V and with an injection current of 300 mA. — ISO
Appl. Phys. Lett. 84, 3394 (2004).