III-nitride based deep ultraviolet light sources

Abstract

We review the physics of deep UV LEDs with emphasis on the features that differ from those for visible LEDs. We discuss UV designs, novel growth process of light generating structures (MEMOCVD^TM) that allows for reducing the growth temperature and improving materials quality, and "phonon engineering" approach that takes advantage of high polar optical energy in AlN/GaN/InN materials for confining electrons in the light emitting quantum wells. We then review the characteristics of DUV LEDs grown on sapphire substrates with peak emission wavelength from 250 to 340 nm that demonstrate the lowest optical noise among all other UV light sources and, therefore, are well suited for the detection of hazardous biological agents using fluorescence techniques. Finally, we describe high power multi-chip, multi-wavelength deep UV light sources and review emerging applications of deep UV LED technology.