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Effects of Surface Layer Defects and Adsorbed Oxygen on TiO2-Rutile Schottky Barriers

Published online by Cambridge University Press:  15 February 2011

M. Levinson*
Affiliation:
Bell Laboratories, Murray Hill, New Jersey 07974, USA
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Abstract

The electronic properties of TiO2 surfaces are of interest to further understanding of grain boundary effects in TiO2 and ZnO based varistor devices. Schottky barriers have been fabricated by Au or Al metallization on Nb doped TiO2-rutile [001] single crystal surfaces. Surface conditions included the presence or absence of either mechanical polishing induced surface defects and/or adsorbed oxygen. I­V measurements on Au samples indicate that surface defects yield ohmic behavior, but the defects may be electrically compensated by adsorbed oxygen to give non-ohmic I­V curves. All Al junctions show ohmic behavior which is interpreted in terms of reaction with surface oxygen. These results explain the necessity of firing varistor materials in an oxidizing atmosphere and suggest that the role of additives in these materials is to stabilize the oxygen concentration at the grain boundaries.

Type
Research Article
Copyright
Copyright © Materials Research Society 1982

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