Thermal chemistry of CH{sub 3} on Si/Cu(100)
Photoelectron spectroscopy (PES), thermal programmed desorption (TPD) studies, and scanning tunneling microscopy (STM) investigated the interaction and chemistry of CH{sub 3} (generated by the thermal cracking of azomethane) on Si/Cu(100). Si was deposited on Cu(100) by the thermal decomposition of SiH{sub 4} at 420 K. STM of adsorbate-free Si/Cu(100) at a less than saturation coverage of Si revealed a surface that contained large domains of a Cu{sub 2}Si structure. These Cu{sub 2}Si domains coexisted with regions that were believed to be lower in fractional Si coverage. TPD results showed that (CH{sub 3}){sub 3}SiH desorbed near 200 K from CH{sub 3}/Si/Cu(100) prepared with a low Si concentration. With increasing Si concentration a (CH{sub 3}){sub 3}SiH desorption state appeared near 420 K, in addition to the 200 K state. The two observed TPD states of (CH{sub 3}){sub 3}SiH at 200 and 420 K were believed to be due to the thermal reaction of CH{sub 3} with the low Si density and high Si density (i.e., Cu{sub 2}Si) regions, respectively. At a saturation coverage of Si, when the well ordered Cu{sub 2}Si phase covered the surface, only the 420 K peak was present during CH{sub 3}/Si/Cu(100) TPD. Results also suggested that (CH{sub 3})Si and possibly some (CH{sub 3}){sub 2}Si intermediates predominated on the surface below room temperature, and (CH{sub 3}){sub 3}Si species were formed on the surface only at temperatures between 250 and 390 K. Surface hydrogen needed for the final evolution of (CH{sub 3}){sub 3}SiH was generated from methyl groups at temperatures above 390 K on the Si-saturated Cu(100).
- Research Organization:
- Temple Univ., Philadelphia, PA (US)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 20034433
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Vol. 104, Issue 14; Other Information: PBD: 13 Apr 2000; ISSN 1089-5647
- Country of Publication:
- United States
- Language:
- English
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