Transparent and semitransparent conducting film deposition by reactive-environment, hollow cathode sputtering

A. E. Delahoy, S. Y. Guo

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49 Scopus citations


Highly transparent and conductive In2 O3 and ZnO films containing different doping elements such as Ti, Mo, Zr, Nb, Ta, W (for In2 O3), and B (for ZnO) have been prepared by reactive-environment, hollow cathode sputtering (RE-HCS). The use of Nb and W as effective dopants is reported for the first time. Metallic targets were used exclusively, and the dopant concentration was easily controlled using a second sputtering power supply. As a result of the cathode and gas flow geometry, the sputtering is conducted in metal mode, and the target and doping materials are free from oxidation during the deposition process. Film resistivities achieved with the various dopants are reported. For In2 O3: Mo (IMO), a resistivity of 1.6× 10-4 Ω cm and a mobility of 80 cm2 Vs were achieved for Mo concentrations in the range 0.5-5.0% as measured by inductively coupled plasma (ICP). X-ray photoelectron spectroscopy (XPS) analysis indicates Mo with a +6 valence state and that the film is stoichiometric. For In2 O3: Ti (ITiO), a superior optical transmission is achieved relative to IMO, while carrier mobility and conductivity were similar. Remarkably, semitransparent films of InN:O having sheet resistances of 9.5 Ωsquare have also been prepared. ZnO:B films deposited by RE-HCS exhibit superior optical properties relative to ZnO:Al, and when applied as a window layer to CIGS solar cells yield higher quantum efficiencies.

Original languageEnglish (US)
Pages (from-to)1215-1220
Number of pages6
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Issue number4
StatePublished - Jul 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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