Accession Number:

ADA222327

Title:

An ESDIAD Study of Chemisorbed Hydrogen on Clean and H-Exposed Si(111)- (7x7)

Descriptive Note:

Technical rept.

Corporate Author:

PITTSBURGH UNIV PA SURFACE SCIENCE CENTER

Report Date:

1990-05-11

Pagination or Media Count:

37.0

Abstract:

The chemisorption of H on Silicon111-7x7 has been studied by digital ESDIAD and temperature programmed desorption methods. It has been found that residual Hydrogen in the bulk of the Si111 can be transported to the surface upon annealing to temperatures above approx. 1000 K. The adsorption of atomic H on Si111-7x7 results in a mixture of monohydride and polyhydride species as detected by HESDIAD. Thermal desorption from the H-saturated surface liberates Beta 3-, Beta 2- B1 - H2 species as well as SiH4g. Heating the H-saturated surface to 1040 K results in a significant disordering of the surface, leading to Si sites which produce highly tilted Si-h bond directions. The occupation of these sites with H produces surface species exhibiting high polar angles from the surface normal for H desorption by an ESD process with a high ionic cross section compared to the cross section observed for normal mono- and polyhydride surface species. JG

Subject Categories:

  • Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE