Nanoscale structure of Si/SiO2/organics interfaces.
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 SiO2 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.
Crystallography and Structural Physics, University of Erlangen-Nürnberg , 91058 Erlangen, Germany.
Hans-Georg
HG
Steinrück
Andreas
A
Schiener
Torben
T
Schindler
Johannes
J
Will
Andreas
A
Magerl
Oleg
O
Konovalov
Giovanni
G
Li Destri
Oliver H
OH
Seeck
Markus
M
Mezger
Julia
J
Haddad
Moshe
M
Deutsch
Antonio
A
Checco
Benjamin M
BM
Ocko
X-ray reflectivity; native silicon oxide; self-assembled monolayers; thin films