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Role of Surfaces and Interfaces for the Electronic Properties of Conducting Oxides

Published online by Cambridge University Press:  21 March 2011

Andreas Klein
Andreas Klein*
Affiliation:
Institute of Materials Science, Darmstadt University of TechnologyPetersenstrasse 23, 64287 Darmstadt, Germany
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Abstract

Transparent conductive oxides (TCOs) are generally considered as degenerate semiconductors doped intrinsically by oxygen vacancies and by intentionally added dopants. For some applications a high work function is required in addition to high conductivity and it is desired to tune both properties independently. To increase the work function, the distance between the Fermi energy and the vacuum level must increase, which can be realized either by electronic surface dipoles or by space charge layers. Photoelectron spectroscopy data of in-situ prepared samples clearly show that highly doped TCOs can show surface band bending of the order of 1 eV. It is further shown that the band alignment at heterointerfaces between TCOs and other materials, which are crucial for many devices, are also affected by such band bending. The origin of the band bending, which seems to be general to all TCOs, depends on TCO thin film and surface processing conditions. The implication of surface band bending on the electronic properties of thin films and interfaces are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 666: Symposium F – Transport and Microstructural Phenomena , 2001 , F1.10
Copyright
Copyright © Materials Research Society 2001

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