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Influence of the deposition temperature on electronic transport and structural properties of radio frequency magnetron-sputtered Zn1-xMgxO:Al and ZnO:Al films

Published online by Cambridge University Press:  04 May 2012

André Bikowski  and
Klaus Ellmer
André Bikowski*
Affiliation:
Department of Solar Fuels and Energy Storage Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
Klaus Ellmer
Affiliation:
Department of Solar Fuels and Energy Storage Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
*
a)Address all correspondence to this author. e-mail: andre.bikowski@helmholtz-berlin.de
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Abstract

ZnO:Al and Zn1-xMgxO:Al films have been deposited by magnetron sputtering from ceramic targets at substrate temperatures from room temperature to 500 °C. We studied the relation between the electronic transport and the structural properties as a function of the deposition temperature. Films with the lowest resistivity (7·10−4 Ω cm for ZnO:Al and 3.6·10−3 Ω cm for Zn1-xMgxO:Al) can be prepared for deposition temperatures around 300 °C. This optimum is accompanied by the highest carrier concentration and the highest Hall mobility. Changes in crystalline quality and free carrier concentration are explained as a result of a bombardment of the films by high energetic negative oxygen ions during growth and by phase segregation for higher deposition temperatures. The dependence of the Hall mobility on the carrier concentration can be explained by grain barrier scattering for n <≈ 5·1020 cm−3 and by ionized impurity scattering for n >≈ 5·1020 cm−3. From the fit of the μ(n) dependence for both materials a trap density at grain boundaries of Nt ≈ 2.3·1013 cm−2 was determined.

Keywords

Transparent conductorSputteringElectrical properties
Type
Articles
Information
Journal of Materials Research , Volume 27 , Issue 17: Focus Issue: Oxide Semiconductors , 14 September 2012 , pp. 2249 - 2256
Copyright
Copyright © Materials Research Society 2012

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