Macropore density as a function of HF-concentration and bias

• Published in: Electrochimica acta Vol. 53; no. 2; pp. 823 - 828
• Main Authors: Bao, X.Q., Lin, J.L., Jiao, J.W., Wang, Y.L.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.2007; Elsevier
• Subjects: Chemistry; Current-burst-model; Electrochemistry; Exact sciences and technology; General and physical chemistry; HF concentration; Macropore density; Miscellaneous (electroosmosis, electrophoresis, electrochromism, electrocrystallization, ...); Penetrating and focusing power; SCR width; Current-burst-model; Macropore density; Penetrating and focusing power; HF concentration; SCR width; Bias; Space charge; One dimensional structure; Density; Porous material; Modeling; Engraving; Focusing; Hydrofluoric acid; Concentration effect; Models; Silicon; Physicochemical properties; Macroporosity
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2007.07.065

Usually, n-macropore density was determined by SCR (space charge region) width. In this paper, under both constant-voltage and galvanostatic conditions, a markedly positive correlation between pore density and HF concentration was evidenced despite a fixed SCR width on low-doped n-Si; the phenomena observed differ a bit from the results dependent on SCR effects. Based on breakdown mechanism and current-burst-model (CBM), an interpretation was given. Additionally, for a given electrolyte and illumination, the correlation between pore density and etching voltage was also found to be considerably positive: both penetrating and focusing power of field strength was supposed to be the underlying factors. The as-produced macropores could be probably significant due to their high density, fast etch-rate and good controllability.