Nano-Micro Letters

Schottky photodiode using submicron thick diamond epilayer for flame sensing

Y. Koide1,*, M. Y. Liao1,*, J. Alvarez2M. Imura3K. Sueishi4F. Yoshifusa4 Abstract
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Nano-Micro Letters, , Volume 1, Issue 1, pp 30-33
Publication Date (Web): November 25, 2009 (Article)




Figure 1 Luminescent spectra of an alcohol lamp flame and solar radiation through a room window.

The sensing of a flame can be performed by using wide-bandgap semiconductors, which offer a high signal-to-noise ratio since they only response the ultraviolet emission in the flame. Diamond is a robust semiconductor with a wide-bandgap of 5.5 eV, exhibiting an intrinsic solar-blindness for deep-ultraviolet (DUV) detection. In this work, by using a submicron thick boron-doped diamond epilayer grown on a type-Ib diamond substrate, a Schottky photodiode device structure- based flame sensor is demonstrated. The photodiode exhibits extremely low dark current in both forward and reverse modes due to the holes depletion in the epilayer. The photodiode has a photoconductivity gain larger than 100 and a threshold wavelength of 330 nm in the forward bias mode. CO and OH emission bands with wavelengths shorter than 330 nm in a flame light are detected at a forward voltage of -10 V. An alcohol lamp flame in the distance of 250 mm is directly detected without a focusing lens of flame light.



Flame sensing; Boron-doped diamond; Schottky photodiode


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