Evaporation Process in Porous Silicon: Cavitation vs Pore Blocking

• Published in: Langmuir 2021-12, Vol.37 (49), p.14419-14428
• Main Authors: Bossert, Marine, Grosman, Annie, Trimaille, Isabelle, Souris, Fabien, Doebele, Victor, Benoit-Gonin, Aristée, Cagnon, Laurent, Spathis, Panayotis, Wolf, Pierre-Etienne, Rolley, Etienne
• Format: Article
• Language: English
• Subjects: Condensed Matter; Physics
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/acs.langmuir.1c02397

We measured sorption isotherms for helium and nitrogen in wide temperature ranges and for a series of porous silicon samples, both native samples and samples with reduced pore mouth, so that the pores have an ink-bottle shape. Combining volumetric measurements and sensitive optical techniques, we show that, at a high temperature, homogeneous cavitation is the relevant evaporation mechanism for all samples. At a low temperature, the evaporation is controlled by meniscus recession, the detailed mechanism being dependent on the pore length and mouth reduction. Native samples and samples with ink-bottle pores shorter than 1 μm behave as an array of independent pores. In contrast, samples with long ink-bottle pores exhibit long-range correlations between pores. In this latter case, evaporation takes place by a collective percolation process and not by heterogeneous cavitation as previously proposed. The variety of evaporation mechanisms points to porous silicon being an anisotropic three-dimensional pore network rather than an array of straight independent pores.