| dc.description | Titanium dioxide (TiO2) films have been the subject of extensive studies for various applications in
last few decades. Many studies focus on the use of dopants, such as niobium (Nb) to modify their
electronic structure, producing optical, electrical, catalytic, and photocatalytic modifications in the
films. This paper presents results of titanium dioxide films doped with niobium. The films were
deposited through a high-power impulse magnetron sputtering (HiPIMS) system using titanium
target 2 inches in diameter. The Ti target disc was provided with Nb inserts attached to holes
distributed in the erosion zone. Films containing different Nb/Ti ratios were obtained by varying
the plasma power from 50 W to 150 W. The samples were characterized through optical
transmittance and reflectance spectroscopies, Hall resistivity, X-ray diffraction (XRD), and X-ray
photoelectron spectroscopy (XPS). The XRD results show that the Nb doped TiO2 films were free of
niobium oxides, which indicates that Nb atoms were incorporated into the TiO2 crystal lattice. The
XPS analysis suggested that the electronic structure of Ti4+ states was altered due to the presence
of pentavalent Nb replacing the tetravalent Ti. Electrical resistivity measurements indicated
reduction in resistivity by several orders of magnitude due to same reason: the extra electrons of
the niobium atoms were ejected in the conduction band, changing the electronic distribution in the
crystalline lattice and consequently reducing its resistivity. The transmittance and reflectance
measurements were similar to those of uncoated glass. Optical transmittance and reflectance
measurements associated to Tauc model, allowed to obtain the band gap width that was shifted to
the red region, indicating that these compounds can be successfully used as transparent
conducting oxide (TCO) films. | |
