The interaction of xenon difluoride with Si(100)

The interaction of low energy XeF2 with Si(100)2x1 has been investigated by studying both the surface-bound and gas-phase products of the reaction. Helium atom diffraction, beam-surface scattering and thermal desorption measurements are the major techniques used to probe the surface-bound products of the reaction. It is found that XeF2 dissociatively chemisorbs with high probability solely on the Si dangling bonds up to a coverage of about one monolayer (ML). Molecular fluorine has previously been observed to react similarly, saturating the dangling bonds at 1 ML coverage. The thermal desorption products and kinetics from the fluorinated layer produced by XeF2 exposure are identical to that produced by F2 exposure. The interactions of XeF2 and F2 are also strikingly similar with respect to the order of the Si surface up to about 1 ML coverage. The surface order is monitored by He diffraction detected by a line-of-sight, differentially pumped mass spectrometer. In both systems, the diffracted He beams exhibit a sharp decrease in intensity due to the disorder produced by the fluorination of random surface unit cells as the coverage increases from zero to about 0.3 ML. The intensity then increases until the fluorine overlayer has fully recovered its 2x 1 periodicity at about 1 ML. This recovery corresponds to the decoration of each Si dangling bond with a fluorine atom. A critical observation of this study is that despite the large exothermicity of the dissociative chemisorption of XeF2 or F2, which is approximately 230-250 kcal/mol, the order of the surface is not destroyed in either system. After saturation of the dangling bonds, F2 ceases to react with the surface while XeF2 continues to deposit fluorine by reacting with the Si-Si a dimer bonds and the Si-Si lattice bonds.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Holt, Judson Robert, 1974-

Advisor dc:contributor.advisor

• Sylvia T. Ceyer.

• Chemistry.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8052

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8052