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7 April 1999 AlGaN-based photodetectors for solar UV applications
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In the recent years, the depletion of the stratospheric ozone layer has alerted the scientific community about the risks of a solar ultraviolet (UV) radiation overexposure. Biological research has confirmed the very important role of the UV-B (320 - 280 nm) and UV-A (400 - 320 nm) bands on the Earth biosystem. AlxGa1-xN semiconductor alloys, with a bandgap tunable between 3.4 eV and 6.2 eV, are the most suitable materials for the fabrication of solar UV detectors. In this paper we describe the fabrication and characteristics of AlGaN photoconductive and Schottky barrier photodetectors, with Al mole fractions up to 35%. Photoconductive detectors show very high gains, that decrease with increasing incident optical power. They present persistent photoconductivity effects, and a significant below-the-gap response. The physics of this behavior is discussed. On the other hand, AlGaN Schottky barrier photodetectors show a very fast response that is independent of the optical power, and their UV/visible rejection ratio is rather high. As the Al content increases, the evolution of the responsivity and cut-off wavelength is presented. Al0.22Ga0.78N Schottky barriers are very good candidates to monitor the UV-B band. The prospective applications of AlGaN photodiodes to determine the biological action of the solar UV radiation are also discussed.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Elias Munoz Merino, E. Monroy, Fernando Calle, Miguel A. Sanchez, Enrico Calleja, Franck Omnes, Pierre J. L. Gibart, Francisco Jaque, and Inigo Aguirre de Carcer "AlGaN-based photodetectors for solar UV applications", Proc. SPIE 3629, Photodetectors: Materials and Devices IV, (7 April 1999);


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