An angular dependent X-ray photoemission study of indium-tin-oxide surfaces

H. H. Fong*, W. J. Song, Shu Kong So

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


The surface properties of indium-tin-oxide (ITO) thin films treated by UV ozone or plasma were analyzed by angular dependent X-ray photoelectron spectroscopy (ADXPS) and by ultraviolet photoemission (UPS). The chemical composition, chemical states and the work function of the ITO surfaces were deduced. Our analysis indicate that ITO surface is Sn-rich. Both UV ozone and O-plasma treatments are most effective in removing surface hydrocarbon. Among all treatments, O-plasma treated surface achieved the highest work function of 4.4eV, whereas argon ion sputtered surface had the lowest work function of 3.9eV. Both O-plasma and UV ozone treatments increase the surface oxygen concentration. It is proposed that O2- ions diffuse into ITO. The diffusion length is about 50Å as deduced from ADXPS. The stoichiometry of the surface is the major factor in controlling the surface work function of ITO. A surface band bending model is proposed to account for the change of work function due to "oxidized""ITO surface after UV-ozone or oxygen plasma treatments.

Original languageEnglish
Pages (from-to)213-219
Number of pages7
JournalMaterials Research Society Symposium Proceedings
Publication statusPublished - 2003
EventCrystalline Oxide-Silicon Heterostructures and Oxide Optoelectronics - Boston, MA, United States
Duration: 2 Dec 20024 Dec 2002

Scopus Subject Areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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