Accession Number:

ADA207734

Title:

Chemical Effects of Ne+ Bombardment on the MoS2(0001) Surface Studied by High-Resolution Photoelectron Spectroscopy

Descriptive Note:

Technical rept.

Corporate Author:

AEROSPACE CORP EL SEGUNDO CA CHEMISTRY AND PHYSICS LAB

Report Date:

1989-03-28

Pagination or Media Count:

35.0

Abstract:

The effect of 1-keV Neon cation bombardment on the clean Molybdenum disulfide 0001 - 1 x1 surface with fluences between 4 x 10 to the 14th power Nesq. cm was studied using high-resolution photoelectron spectroscopy excited with synchrotron radiation. Spectra of the Mo-3d and S-2p core levels were measured with photon energies that ensured that the kinetic energy of their photoelectrons was the same, resulting in the same depth being probed for both core levels. For lower fluences, S vacancy defect formation occurs in the MoS2 lattice, with the concurrent formation of a small amount 10 of dispersed elemental molybdenum Mo0. For fluences greater than approx. 1 x 10 to the 16th power Nesq. cm, the Mo0 is the predominant species in the surface region, while the remaining species consists of amorphous MoS2-xand polysulfide species. Valence band spectra taken with photon energies of 152 eV and 225 eV were consistent with the core level results. The movement of the valence band maximum toward the Fermi level indicated the formation of a metallic surface region. A qualitative depth distribution of the chemical species present after Ne bombardment was determined. The result indicate that the preferential sputtering of sulfur over molybdenum occurs predominantly through a mechanism involving chemical bonding effects, specifically, through the preferential emission of polysulfide ions over other species in the bombarded region.

Subject Categories:

  • Physical Chemistry
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE