Transport mechanisms of RF sputtered Al-doped ZnO films by H

M.L. Addonizio, A. Antonaia, G. Cantele, C. Privato

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Abstract

Aluminum-doped ZnO thin films, with a doping level in the range 2-2.8 at.%, were deposited by RF magnetron sputtering. Sputtering processes with pure Ar and Ar/H2gas mixtures have been explored. Electrical conductivity and Hall mobility of ZnO:Al films were measured in a wide temperature range. It has been found that the addition of hydrogen to the sputtering gas is an effective method to modify the morphological, structural and electrical properties of the ZnO:Al films. A low hydrogen dilution is able to produce a noticeable improvement of the conductivity by means of a better effectiveness of the Al doping. ZnO:Al films deposited at low hydrogen dilution showed a columnar structure whereas at high hydrogen dilution spherical shaped domains were present, formed by many stacked crystallites. Carrier mobility for the former structure was limited by bulk mechanisms, particularly by acoustical phonon and ionized impurity scattering. Carrier mobility for the latter structure was limited by grain boundary mechanisms, particularly by tunnelling effect between neighbouring spherical macro-aggregates.
Original languageEnglish
Pages (from-to)93 - 99
Number of pages7
JournalThin Solid Films
Volume349
Issue number1
DOIs
Publication statusPublished - 30 Jul 1999

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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