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Keywords:

  • 78.66.Hf;
  • 81.05.Dz;
  • 81.15.Cd

Abstract

We report on the optical and structural properties of a series of ZnO1−xSx films deposited by radio-frequency sputtering on float glass and sapphire substrates. In the range 0 < x < 0.4 we find that the films have wurtzite symmetry and the lattice constant varies linearly on the composition as confirmed by photoelectron spectroscopy and Rutherford backscattering. Raman measurements show that the spectral position of the A1(LO) mode is sensitive to the sulfur content in the films. The composition dependence of the band gap was evaluated by analyzing the absorption coefficient as a function of the square root of the photon energy (direct transition). The energy gap shifted by more than 500 meV to lower energies indicating a bowing of appr. 2.5 eV in contrast to previous predictions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)