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Highly (111) oriented Bi2Ti2O7 thin films have been grown on Pt∕Ti∕SiO2∕Si and Al2O3 substrates by metalorganic decomposition method at 550°C. The structural properties of the films were examined by x-ray diffraction. The Bi2Ti2O7 films exhibit good insulating property and the leakage current density of the film on Pt∕Ti∕SiO2∕Si is only about 1.56×10−8A∕cm2 at 200kV∕cm. The refractive index and extinction coefficient of Bi2Ti2O7 thin films were determined by fitting the infrared spectroscopic ellipsometric data using a classical dielectric function formula. As the wavelength increases, the refractive index decreases, while the extinction coefficient increases. And the band-gap energy Eg was obtained from the optical transmission spectra of Bi2Ti2O7 thin films.

Bi3.25La0.75Ti3O12 (BLT) thin films have been grown on n-type Si (100) substrates by metalorganic decomposition method. The structural properties of the films were examined by x-ray diffraction. The BLT films exhibit good insulating property with room temperature resistivities in the range of 1012–1013 Ω cm. The current–voltage characteristics show ohmic conductivity in the lower voltage range and space-charge-limited conductivity in the higher voltage range. The capacitance–voltage characteristic hysteresis curves show that the metal-ferroelectric-semiconductor structure has memory effect. The fixed charge density and the surface state density were also calculated. The results obtained indicate that the present BLT films are suitable for making ferroelectric field effect transistor memories.

Polycrystalline films of Mn1.56Co0.96Ni0.48O4 (MCN) were evaluated for uncooled bolometric applications grown by chemical solution deposition on amorphous Al2O3 substrate. The microstructural characterizations showed that the films were of excellent crystallization and compact surface morphology. Electrical results showed that the temperature coefficient of resistance reached −3.8%/K at 295 K. Low excess noise (normalized Hooge parameter αH/n of 7.6 × 10−28 m3) was achieved owing to the good epitaxial quality of the prepared films. Infrared bolometers were fabricated to evaluate the performance on infrared detection. It exhibited a noise equivalent temperature as low as 2.1 × 10−7 K/Hz1/2, responsivity of 330 V/W, detectivity of 0.6 × 108 cm Hz1/2/W, and noise equivalent power of 3.7 × 10−10 W/Hz1/2 at 30 Hz. The feasibility of the MCN films was demonstrated to be used for uncooled bolometric applications by thermal imaging. One can expect to get a responsivity of about 1 × 103 V/W and detectivity higher than 6 × 108 cm Hz1/2/W at 30 Hz for thermally isolated MCN film bolometer. The results of MCN showed its great potentiality for future room-temperature detection.

The temperature dependent dc resistivity of spinel Mn1.56Co0.96Ni0.48O4 (MCN) films is measured in the range of 130–304 K. The hopping exponent p of small polaron hopping conduction shows a clear variation from a value of 0.46 in the paramagnetic to 0.91 in the ferromagnetic phase. In order to explain such variation, a model is proposed where Gaussian distributed localized electron states gradually withdraw from the Hubbard band gap below the magnetic transition as a result of increased magnetic order. This correlation between hopping conduction and magnetic order in MCN films may provide a possible approach to fabricate the devices which couple magnetic and electronic properties in one unit.

Mn1.56Co0.96Ni0.48O4 films with spinel structure were prepared on Al2O3 substrate by chemical solution deposition method. The microstructure of the films was studied by atomic force microscope and field-emission scanning electron microscope. The current-voltage characteristics showed Ohmic conductivity in the temperature range of 245–295K. The conduction was described by a variable range hopping model for a parabolic density of states. The advantages of high characteristic temperature, as well as high transition temperature (201K) between ferromagnetic and paramagnetic phases make the Mn1.56Co0.96Ni0.48O4 films very promising for infrared detection, especially for functional devices by integrating magnetic and electronic properties of the materials.

The infrared dielectric constants of the perovskite BaTiO3 are obtained by infrared spectroscopic ellipsometry in the temperature range of 20–150°C. Apparent temperature-dependent distribution of the spectral weight variation is observed for complex dielectric function. Both high frequency dielectric function and bound electrical charge show the temperature dependence from the tetragonal to the cubic phase transition. The bound electrical charge appears to be composed of a hopping component and a temperature-dependent one for BaTiO3 with first-order transitions.

Using infrared spectroscopic ellipsometry, the dielectric functions of (111) oriented Bi2Ti2O7 thin films with pyrochlore structure prepared on Pt∕Ti∕SiO2∕Si substrate were determined in the temperature range of 20–70 °C. It is demonstrated that there is a phase transition that appears near 40 °C in terms of static effective charge as a function of temperature calculated from the infrared spectroscopic ellipsometric data of Bi2Ti2O7 thin films. It suggests that the static effective charge is related to the structural distortion, which can facilitate the polarization of Bi2Ti2O7. Accordingly, ferroelectricity in Bi2Ti2O7 is proved by analyzing the infrared dielectric function.