Preparation of textured and photoactive 2H-WS2 thin films by sulfurization of WO3

A. Ennaoui, S. Fiechter, K. Ellmer, R. Scheer, K. Diesner

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Abstract

Photoactive thin films of tungsten disulfide have been prepared by sulfurization of WO3 layers. Tungsten trioxide films were deposited on heated quartz and glassy carbon substrates by gaseous reaction of W(CO)6 with oxygen. Subsequently, the oxide films were treated at 700 °C in a gaseous sulfur atmosphere either in a flowing system or in evacuated and sealed quartz ampoules. The films were investigated by X-ray diffractometry, scanning electron and scanning tunneling microscopy. The photoactivity was measured using time-resolved microwave conductivity. Films consisting of the 2H-WS2 platelets, highly textured and oriented with their c axis perpendicular to the substrate, were found. In addition, the phase relations in the phase triangle W-O-S were studied by thermochemical equilibrium calculations using the Gibbs free energy minimization technique. The inferred predominance area diagram log Ps2 vs. log pso2 confirms the high stability of WO2,9 and WS2 as observed under related experimental conditions. The effect of the nickel on the orientation of the 2H-WS2 crystallites obtained after sulfurization of the WO3 films can be explained by a flux on the basis of the binary Ni-S phase diagram or surfactant mediated growth effect.

Original languageEnglish
Pages (from-to)124-131
Number of pages8
JournalThin Solid Films
Volume261
Issue number1-2
DOIs
Publication statusPublished - 1 Jun 1995

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Keywords

  • Phase transitions
  • Sulphides
  • Tungsten

ASJC Scopus subject areas

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

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