Nanoscale electrical conductivity and surface spectroscopic studies of indium-tin oxide

Ian Liau, Norbert F. Scherer*, Kent Rhodes

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

76 Scopus citations

Abstract

Optically transparent indium-tin oxide (ITO) is a "universal" electrode for various optoelectronic devices such as organic light emitting diodes (OLEDs). It is known that the performance of OLEDs improves significantly by exposing the ITO surface to an oxygen plasma. This study employs conducting atomic force microscopy (C-AFM) for unique nanometer-scale mapping of the local current density of a vapor-deposited ITO film. The local conductance is shown to increase by orders of magnitude and becomes more uniform after oxygen plasma treatment for measurements of the identical 200-nm2 regions. Scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy measurements of separate regions of the same films suggest that the oxygen plasma removes a thin layer of insulating carbon-rich material from the surface. The extensive heterogeneity in interfacial electrical conductivity measured by C-AFM calls into question previous studies of STM-induced electroluminescence of polymer films on ITO as well as STM imaging of such films. The impact of this study on the future development of optoelectronic devices is discussed.

Original languageEnglish
Pages (from-to)3282-3288
Number of pages7
JournalJournal of Physical Chemistry B
Volume105
Issue number16
DOIs
StatePublished - 26 Apr 2001

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