Influence of metal impurity defects on the electrical and optical properties of ITO films on the PEN substrates

Hauk Han, Terry Alford

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Indium tin oxide (TTO) has drawn a great deal of attention due to its potential use as transparent electrodes in organic light emitting diode (OLED) and photovoltaic applications. This work focuses on understanding the role of impurity defects on the electrical conduction and transmittance of ITO. Thin films of ITO with high carrier concentration have been deposited onto polyethylene napthalate (PEN) substrates by electron-beam deposition without introduction of oxygen into the chamber. The influence of air anneals on the electrical and optical properties of ITO/PEN samples can is evaluated in terms of the oxygen content and is explained in terms of changes in the free electron concentrations. Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy analysis were used to determine the oxygen content in the film. A Hall effect measurement is used to determine the dependence of electrical properties on oxygen content. The electrical properties of the ITO films such as carrier concentration, electrical mobility, and resistivity abruptly changes after annealing in the air atmospheres. In addition, optical transmittance is improved from 7 to 71 % and optical band gap changes from 3.18 to 3.25 eV after heat treatment. The optical band gap narrowing behavior is because of impurity band and heavy carrier concentration. Metal impurity clusters form in the films as a result of oxygen deficiency and also generate defects and/or impurity states in the band gap and produces an optical band gap shift by merging of these impurity states and conduction band.

Original languageEnglish (US)
Title of host publication2007 MRS Spring Meeting
PublisherMaterials Research Society
Number of pages6
ISBN (Print)9781558999725
StatePublished - 2007
Event2007 MRS Spring Meeting - San Francisco, CA, United States
Duration: Apr 9 2007Apr 13 2007

Publication series

NameMaterials Research Society Symposium Proceedings


Conference2007 MRS Spring Meeting
Country/TerritoryUnited States
CitySan Francisco, CA

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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