Enhancement of remanent polarization has been demonstrated in epitaxial “asymmetric” BaTiO3/SrTiO3 strained superlattices, in which the thickness ratio of BaTiO3 to SrTiO3 layers is changed at molecular layer order accuracy. The superlattices have been prepared on Nb-doped SrTiO3 (100) single-crystal substrates by a pulsed-laser deposition technique. The superlattice with a stacking periodicity of 15 unit cells BaTiO3/3 unit cells SrTiO3 shows the largest remanent polarization 2Pr of 46 μC/cm2, which is about three times that of the BaTiO3 single-phase film formed under the same condition. The increase in the remanent polarization is attributed both to the BaTiO3-rich structure and to the increase in lattice parameter c due to the mismatch of in-plane lattice parameters between BaTiO3 and SrTiO3.

Epitaxial BaTiO3(111)/SrTiO3(111) multilayered thin films have been investigated with various periods of stacking layer between 0.45/0.45 and 10/10 nm on Nb-doped SrTiO3(111) substrates by a pulsed-laser deposition technique. Upon decreasing the period of each layer, the spacing of (111) plane (d111) of the multilayered film increases, and the relative dielectric constant goes up to 594 which is twice as large as that of (111) oriented (Ba0.5, Sr0.5)TiO3 solid-solution film. The expansion of d111, which might be attributed to an in-plane pressure effect due to the large lattice strain in the heteroepitaxial interface, contributes to the enlargement of relative dielectric constant. Remanent polarization observed in polarization versus applied voltage hysteresis loop is no more than 2.7 μC/cm2 with 2.0/2.0 nm period of layer.

We have been successful in obtaining temperature-stable crystallized thin film of (Zr,Sn)TiO4. Preferential (111)-oriented (Zr,Sn)TiO4 thin film was prepared by pulsed laser deposition. Effects of crystallization were elucidated based on a comparison of electric properties of crystallized and amorphous (Zr,Sn)TiO4 film. For crystallized film, the temperature coefficient of capacitance (TCC) was 20 ppm/°C at 3 MHz and the dielectric constant εr=38 in the microwave range of 1–10 GHz. These values are superior to those for amorphous film (TCC=220 ppm/°C, εr=27). The crystallization of this material was found quite effective for improving dielectrical properties. Atomic force microscope images showed the surface morphologies of crystallized and amorphous film of (Zr,Sn)TiO4 to differ.

Moisture-resistant ZnO transparent conductive films were formed with Ga heavy doping by off-axis-type rf magnetron sputtering. The resistivity of 12.4wt% Ga-doped ZnO is 1.3×10−3Ωcm and changes by less than 3% over a 2000h reliability test at a temperature of 85°C and a humidity of 85%. The crystal structural analysis of the heavily Ga-doped ZnO films indicates that the c axis grows along various directions, which is quite different from the conventional c-axis oriented growth. The effect of heavy doping is discussed based on the crystal structural transformation and carrier compensation by excess Ga segregated in the film.

SrTiO3 thin film has been formed on Si(100) substrates with various single buffer layers such as SrO, CeO2, CaF2, CoSi2 and a multibuffer layer, YSZ/Y2O3/YBa2Cu3O7 by ArF excimer laser ablation. The relation of lattice orientation of buffer layers with SrTiO3 layer has been elucidated. The orientation of SrTiO3 film is influenced not only by lattice matching but by crystal structure and chemical bonding of the buffer layers. As well, the multibuffer layer more effectively forms preferential c-axis oriented SrTiO3 film on Si(100), while CoSi2 buffer is more effective for improving the dielectric constant of SrTiO3 than other buffer layers.