Accession Number:

ADA248297

Title:

Silicon Backbond Strain Effects on NH3 Surface Chemistry - Si(111)-(7x7) Compared to Si(100)-(2x1)

Descriptive Note:

Technical rept.

Corporate Author:

PITTSBURGH UNIV PA SURFACE SCIENCE CENTER

Report Date:

1992-03-11

Pagination or Media Count:

25.0

Abstract:

The role of surface structure in controlling NH3 surface chemistry has been investigated by HREELS and TPD on Silll-7x7 and Si100-2xl. Following the initial NH3 dissociative adsorption producing NH2a and Ha, the production of NHa species iS favored on Silll-7x7 between 300-600 K. This is believed to occur through the insertion of NHa into the backbond of the Si adatom on Si111-7x7 and to be driven by the relief of bond strain on the Si adatom backbonds. By contrast, this stepwise reaction mechanism is absent on Si1001-2xl. Instead, the surface NH2a species remain thermally stable until -600 K, when a new reaction channel opens up leading to the partial depletion of NH2a by recombination with Ha to form NH3g.

Subject Categories:

  • Inorganic Chemistry
  • Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE