Realization of 270 nm band AlGaN based UV-LEDs on large area AlN templates with high crystalline quality

Semiconductor light-emitting diodes (LEDs) with emission wavelengths in the range 250-350nm have a wide range of potential applications. So far, high power AlGaN- and InAlGaN-based LEDs in the ultraviolet (UV) region have been fabricated. However, for the realization of commercially-available low-cost UV-LEDs, the fabrication of structures on large-sized or multiple wafers is desirable. We have now demonstrated the growth of AlN templates using an ammonia (NH(3)) pulsed-flow multilayer (ML) growth technique and AlGaN based UV-LEDs on (0001) sapphire substrates by low-pressure metalorganic chemical vapour deposition (MOCVD) in a 2 '' x 3 reactor system. In the case of the (1012) X-ray rocking curve (XRC), the full-width-at-half-maximum (FWHM) increased from 510 arcsec to 580 arcsec when scanning from the center to the edge of the wafer. On the other hand, the FWHM of the (0002) XRC was slightly increased from 170 arcsec to 190 arcsec. Furthermore, Emission peaks for UV-LEDs were clearly observed in the range from 268 nm to 284 nm. The output power at 100 mA and maximum output power were 0.2 mW and 0.3 mW, respectively. These results indicate that sub-milliwatt operation in the deep-UV range was successfully achieved. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim