Titanium oxinitride (TiOx
Ny
) solar absorber coatings were deposited at different oxygen partial pressures onto Cu,
Si and glass substrates using electron beam evaporation technique. XRD diffraction
patterns evidenced (111), (200) and (220) orientation of TiNx
phase. The preferred
orientation of the films changed with oxygen partial pressure. XPS revealed the intensity
of both Ti 2P3/2 and Ti 2P1/2 increases as a function of oxygen flow, and also shifted
towards higher binding energy, indicating more oxidized state of Ti species than that
of TiO2
due to incorporation of nitrogen atoms. Formation of uniformly distributed
spherical like particles and an increase in surface roughness of the TiOx
Ny
films were
observed as a function of oxygen partial pressure as depicted from SEM and AFM,
respectively. Ellipsometric and resistivity measurements showed a shift from metallic
to semiconductor behaviour of the TiOx
Ny
films as oxygen flow changed. A solar
absorptance value of 0.94 in the solar spectrum region and a low thermal emittance
value of 0.05 were achieved for the TiOx
Ny
solar absorber coatings prepared at the
oxygen partial pressure of 7.5x10-5 Torr due to both interference and intrinsic absorption. This study confirmed that
a single layer of TiOx
Ny
film can be a good candidate as selective solar absorber.