THz time domain spectroscopy of pulsed laser deposited BaTiO ₃ thin films

We have measured the dielectric properties of pulsed laser deposited 1.1μm thick BaTiO ₃ (BTO) thin films on MgO substrate in the MHz and THz frequency region. The properties of two BTO thin films deposited at substrate temperature 790 and 840°C have been studied. X-ray diffraction pattern and AFM measurement of the films shows that the BTO film grown at temperature 840°C has better epitaxial growth and smooth surface compared to the film grown at 790°C. The dielectric properties of thin films have been measured by THz time domain spectroscopy (THz-TDS) in the frequency range from 0.3 to 2.5THz and by interdigital electrode measurement in the region from 10kHz to 10MHz. The BTO thin film deposited at higher temperature has a higher dielectric constant and tunability in the MHz frequency range whereas at THz frequencies the real and imaginary part of the refractive index and dielectric constant of both films show almost similar behavior.