Study of submonolayer films of Au/Cu(100) and Pd/Cu(100) using positron annihilation induced auger electron spectroscopy

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7045533

Lee, K D

Positron Annihilation induced Auger Electron Spectroscopy (PAES), electron induced Auger Electron Spectroscopy (EAES), and Low Energy Electron Diffraction (LEED) have been used to study the surface composition, surface alloying and overlayer formation of ultrathin films of Au and Pd on Cu(100). This is the first systematic application of PAES to the study of the surface properties of ultrathin layers of metals on metal substrates. Temperature induced changes in the top layer surface compositions in Au/Cu(100) and Pd/Cu(100) are directly observed using PAES, while EAES spectra indicate only minor changes. The surface alloying of the Au/Cu(100) and Pd/Cu(100) systems are demonstrated using PAES in conjunction with LEED. The PAES intensity measurements also provide evidence for positron trapping at surface defects such as steps, kinks and isolated adatoms. The PAES intensity was found to be strongly dependent on surface effects introduced by ion sputtering. The surface defect dependence of the PAES intensity is interpreted in terms of the surface atomic diffusion and positron trapping at surface defects in Au/Cu(100) and Pd/Cu(100). In both systems the shapes of the PAES intensity versus coverage curves for submonolayer coverages at 173K are quite distinct indicating differences in overlayer growth and diffusion behavior of Au and Pd adatoms on the Cu(100) surface. PAES intensities for both Au and Pd are saturated at 1 monolayer demonstrating the extreme surface selectivity of PAES.

• Research Organization: Texas Univ., Arlington, TX (United States)
• OSTI ID: 7045533
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
AUGER ELECTRON SPECTROSCOPY
COATINGS
COHERENT SCATTERING
COPPER
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
FILMS
GOLD
METALS
PALLADIUM
PLATINUM METALS
SCATTERING
SPECTROSCOPY
SPUTTERING
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
THIN FILMS
TRANSITION ELEMENTS