Size analysis of water cluster ions and their irradiation effects on solid surfaces

Gikan H. Takaoka, Kazuya Nakayama, Hidetaka Noguchi, Masakazu Kawashita

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

This article reports the development of a liquid cluster ion source. When water vapor was injected through a nozzle into a high-vacuum region, water clusters were produced at vapor pressures greater than 1 atm. The size of the water cluster ions was measured by the time-of-flight (TOF) method, and it was distributed between a few hundreds and a few tens of thousands of molecules. The intensity of the water cluster ions increased with increase of the vapor pressure, and the peak size was about 2500 molecules per cluster. The effects of irradiation by water cluster ions on solid surfaces such as Si(100) and SiO2 surfaces were investigated. The sputtered depth of the Si and SiO2 surfaces increased with increase of the acceleration voltage, and the SiO2 surfaces were sputtered more than the Si surfaces. The sputtering yields at an acceleration voltage of 9 kV were 17.8 atoms per ion for Si and 17.1 molecules per ion for SiO2, which were approximately ten times larger than that for Ar monomer ion irradiation. Rutherford backscattering spectroscopy (RBS) measurement showed that the number of displacement atoms for irradiation by water cluster ions on the Si surfaces at ion doses larger than 1 × 1015 ions/cm2 was less than that for Ar monomer ion irradiation at the same acceleration voltage. In addition, the ellipsometry and X-ray photoelectron spectroscopy (XPS) measurements showed that the thickness of the oxide layer formed on the Si surface increased with increase of the acceleration voltage, and it was between 10 nm and 15 nm at an acceleration voltage of 9 kV.

Original languageEnglish
Pages (from-to)1534-1538
Number of pages5
JournalSurface and Interface Analysis
Volume38
Issue number12-13
DOIs
Publication statusPublished - 2006 Dec 1

Keywords

  • Cluster ion beam
  • Irradiation damage
  • Oxidation
  • Silicon
  • Sputtering yield
  • Water cluster ion

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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