TiNx and TiNx0y films are deposited by DC reactive bias sputtering in an argon atmosphere with nitrogen and oxygen added as reactive gases. The DC resistivity and deposition rate of biased and non-biased layers have been determined.X-ry and eil,,ctron diffractim are used to investigate the structure of the films. Their composition was investigated using X-ray Facto-electron Spectroscopy (XPS) and Rutherford Back Scattering (RBS) combined with Nuclear Reac-tion Analysis (NRA). The optical properties are investigated in the spectral region 0.4-25 μm. Bias sputtered TiNx films show a low resistivity and a solar absorptance which is too low for practical use as a spectrally selective absorbing layer in a solar collector. Non-biased films, sputtered in an argon/nitrogen atmosphere, and TiNx0y films, bias sputtered with oxygen added to the glow discharge, show a much higher resistivity and a higher solar absorptance. The solar absorptance of spectrally selective TiNxOy/copper tandems is moderate (0.80-0.85) but their thermal emittance is low (0.05 at 1500C). Heat treatment for 12 h at 4000C in vacuum hardly affects the optical properties.
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