Nanoscale Structure of Si/SiO sub(2)/Organics Interfaces

• Published in: ACS nano Vol. 8; no. 12; pp. 12676 - 12681
• Main Authors: Steinrueck, Hans-Georg, Schiener, Andreas, Schindler, Torben, Will, Johannes, Magerl, Andreas, Konovalov, Oleg, Destri, Giovanni Li, Seeck, Oliver H, Mezger, Markus, Haddad, Julia, Deutsch, Moshe, Checco, Antonio, Ocko, Benjamin M
• Format: Journal Article
• Language: English
• Published: 03.02.2014
• Subjects: Density; Nanostructure; Reflectivity; Silicon; Silicon dioxide; Silicon substrates; Thin films; X-rays
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn5056223

X-ray reflectivity measurements of increasingly more complex interfaces involving silicon (001) substrates reveal the existence of a thin low-density layer intruding between the single-crystalline silicon and the amorphous native SiO sub(2) terminating it. The importance of accounting for this layer in modeling silicon/liquid interfaces and silicon-supported monolayers is demonstrated by comparing fits of the measured reflectivity curves by models including and excluding this layer. The inclusion of this layer, with 6-8 missing electrons per silicon unit cell area, consistent with one missing oxygen atom whose bonds remain hydrogen passivated, is found to be particularly important for an accurate and high-resolution determination of the surface normal density profile from reflectivities spanning extended momentum transfer ranges, now measurable at modern third-generation synchrotron sources. Keywords: X-ray reflectivity; thin films; native silicon oxide; self-assembled monolayers