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The Effect of Atmospheric Doping on the Interfacial Electronic Structure of Phthalocyanine Thin Films as Studied by UPS

Published online by Cambridge University Press:  01 February 2011

Toshio Nishi
Affiliation:
Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
Kaname Kanai
Affiliation:
Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
Yukio Ouchi
Affiliation:
Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
Martin R. Willis
Affiliation:
School of Chemistry, The University of Nottingham, University Park, Nottingham. NG7 2RD. UK
Kazuhiko Seki
Affiliation:
Research Center for Materials Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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Abstract

The effect of oxygen doping on titanyl phthalocyanine (TiOPc) films was investigated by ultraviolet photoelectron spectroscopy (UPS). The energy of the electronic levels of TiOPc films probed by UPS was clearly different between the film deposited in ultrahigh vacuum (UHV) and in oxygen atmosphere. The film deposited in UHV showed downward band bending characteristic of n-type semiconductor. On the other hand, the film deposited in oxygen atmosphere showed upward band bending characteristic of p-type semiconductor. Such trends are in excellent correspondence with reported field effect transistor characteristics. In order to examine the Fermi level (EF) alignment between TiOPc film and the substrate, the HOMO energy of TiOPc relative to the EF of the metal substrate was determined for various substrates. Although EF alignment was not achieved for the TiOPc film prepared in UHV, possibly because of insufficient charge density in the TiOPc film, it was achieved in the case of TiOPc film exposed to oxygen, probably by p-type doping effect of oxygen.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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