Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys

Solid-state light sources emitting at wavelengths less than 300 nm would enable technological advances in many areas such as fluorescence-based biological agent detection, non-line-of-sight communications, water purification, and industrial processing including ink drying and epoxy curing. In this paper, we present our recent progress in the development of LEDs with emission between 237 and 297 nm. We will discuss growth and design issues of deep-UV LEDs, including transport in Si-doped AlGaN layers. The LEDs are designed for bottom emission so that improved heat sinking and light extraction can be achieved by flip chipping. To date, we have demonstrated 2.25mW of output power at 295 nm from I mm x I mm LEDs operated at 500 mA. Shorter wavelength LEDs emitting at 276 nm have achieved an output power of 1.3 mW at 400 mA. The heterostructure designs that we have employed have suppressed deep level emission to intensities that are up to 330 x lower than the primary quantum well emission. (C) 2004 Published by Elsevier B.V.