Journal of Materials Research

Reviews

Reactive magnetron sputtering of transparent conductive oxide thin films: Role of energetic particle (ion) bombardment

Klaus Ellmera1 c1 and Thomas Welzela1

a1 Helmholtz-Zentrum für Materialien und Energie GmbH, 14109 Berlin, Germany

Abstract

Transparent conductive oxides (TCOs) are degenerately doped compound semiconductors with wide band gaps (E g > 3 eV), which are used as transparent electrodes in optoelectronic devices. Reports on the influence of negative ions on the electrical properties of TCO films are reviewed and compared with our results. It was reported that the radial resistivity distributions depend (i) on the excitation mode of the magnetron (direct current or radio frequency), (ii) on the erosion state of the sputtering target, and (iii) on the density of the ceramic targets. This can be explained by the fact that the negative ions in magnetron discharges (in our case O) are generated at the target surface and accelerated toward the growing films. Their energy and their radial distribution depend on the discharge voltage and the shape of the emitting surface, i.e., of the erosion groove. Ways for reducing the effect of negative ion bombardment are discussed.

(Received September 23 2011)

(Accepted November 22 2011)

(Online publication February 08 2012)

Key Words:

  • Plasma deposition;
  • Transparent conductor;
  • Electrical properties

Correspondence:

c1 Address all correspondence to this author. e-mail: ellmer@helmholtz-berlin.de

Footnotes

This section of Journal of Materials Research is reserved for papers that are reviews of literature in a given area.

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