Efficient photothermal conversion requires surfaces of high solar absorptance and low thermal emittance. This can be accomplished by the tandem action of a good infrared reflector overlaid by a film of sufficient solar absorptance that is transparent in the infrared. Crystalline silicon is a suitable candidate for the absorber layer. Its indirect band gap, however, results in a shallow absorption edge that extends to far into the visible. In contrast, the absorption edge of amorphous silicon is steeper and located farther into the infrared, resulting in a larger solar absorptance. We report on the fabrication of amorphous silicon absorbers by chemical vapor deposition (CVD). Their optical and structural properties are determined as a function of the deposition temperature. We describe the effects of a progressive crystallization during anneal above 650 °C and report the performance of converter stacks that are identical "twins" except for the use of a polycrystalline silicon absorber in one and an amorphous absorber in the other.

Original Publication Citation

D.C. Booth, M. Janai, G. Weiser, David D. Allred, and B.O. Seraphin, "Chemical Vapor Deposited Amorphous Silicon for Use in Photothermal Conversion," Optics Applied to Solar Energy IV, Proceedings of SPIE 161, 72 77 (1978). http://spie.org/x648.html?product_id=956874

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Peer-Reviewed Article

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Society of Photo Optical Instrumentation Engineers (SPIE)




Physical and Mathematical Sciences


Physics and Astronomy