Pulsed Laser Porosification of Silicon Thin Films
Institute for Photovoltaics and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany
Author to whom correspondence should be addressed.
Academic Editor: Giorgio Biasiol
Received: 1 June 2016 / Revised: 17 June 2016 / Accepted: 21 June 2016 / Published: 24 June 2016
We present a new and simple laser-based process to porosify thin film silicon using a pulsed laser. During deposition, we incorporate gas atoms or molecules into the Si thin film. Pulsed laser radiation of wavelength
heats up thin film Si beyond its melting point. Upon heating, gas atoms or molecules form nm-sized thermally expanding gas bubbles in the silicon melt, until they explosively exit the film, leaving pores behind. Rapid heating and fast cooling during pulsed laser processing enable re-solidification of the liquid Si before the created pores contract and pore closure occurs within the liquid phase. Optimized plasma-enhanced chemical vapor deposition or sputtering of amorphous Si thin films on stainless steel substrate incorporates the necessary concentration of gas atoms or molecules. We are able to tailor the pore size between 50 and 550 nm by changing laser pulse energy density and film deposition parameters. Evaporated silicon containing no gas atoms forms only a few very large
m-sized gas bubbles due to laser-induced vapor formation of evaporated solid material at the substrate–silicon interface.
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MDPI and ACS Style
Sämann, C.; Köhler, J.R.; Dahlinger, M.; Schubert, M.B.; Werner, J.H. Pulsed Laser Porosification of Silicon Thin Films. Materials 2016, 9, 509.
Sämann C, Köhler JR, Dahlinger M, Schubert MB, Werner JH. Pulsed Laser Porosification of Silicon Thin Films. Materials. 2016; 9(7):509.
Sämann, Christian; Köhler, Jürgen R.; Dahlinger, Morris; Schubert, Markus B.; Werner, Jürgen H. 2016. "Pulsed Laser Porosification of Silicon Thin Films." Materials 9, no. 7: 509.
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