Synthesis of niobium-doped hexagonal barium titanate thin films by laser ablation

Niobium doped hexagonal barium titanate Ba1NbxTi1-xO3 thin films have been successfully synthesized on sapphire (00 (0) over bar 1) substrates by laser ablation. These films were synthesized for different concentrations of niobium under various conditions. We have observed the well oriented thin films along the c-axis of the substrate by the X-ray diffraction. These films were deposited at the substrate temperature of 700 degrees C both in the oxygen and nitrogen atmospheres. A resistance as high as 2 M Omega has been measured by the usual multimeter at room temperature. A large negative thermopower similar or equal to 300 mV/K at room temperature has also been measured for these films. Rutherford backscattering spectrometry (RES) was performed on very thin films of this system for different concentration of niobium deposited in the N-2 atmosphere. We have found the deficiency of Ti elements in these films by RES analysis, which may be a cause of high resistance and large thermopower in these films.