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

Published online by Cambridge University Press:  11 February 2011

H. H. Fong ,
W. J. Song  and
S. K. So
H. H. Fong
Affiliation:
Department of Physics and Center for Surface Analysis and Research, Hong Kong Baptist University, Hong Kong, P.R. China
W. J. Song
Affiliation:
Department of Physics and Center for Surface Analysis and Research, Hong Kong Baptist University, Hong Kong, P.R. China
S. K. So
Affiliation:
Department of Physics and Center for Surface Analysis and Research, Hong Kong Baptist University, Hong Kong, P.R. China
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Abstract

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.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 747: Symposia T/V – Crystalline Oxides on Semiconductors – Interfacial Issues for Oxide-Based Electronics , 2002 , V1.7
Copyright
Copyright © Materials Research Society 2003

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References

REFERENCES

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