Ca-Mg-Si films were firstly prepared on (001)Al2O3 substrates by RF-magnetron sputtering method from Mg disc target together with Ca and Si chips. The composition of the deposited films was controlled by adjusting deposition temperature and Ca/Si area ratio of Ca and Si chips on Mg disk target. Ca0.32Mg0.33Si0.35 film deposited at 610 K consisted of a single phase of CaMgSi and this CaMgSi phase was stable after heat treated at 770 K under an atmospheric Ar with 5% -H2. As-deposited film shows the semiconductor behavior and have a power factor of 50 μW/(mK2) at 670 K, while annealed one showed the metallic behavior and its power factor down below 10 μW/(mK2) at 320-770 K. On the other hand, Ca0.27Mg0. 51Si0.2 film deposited at 590 K showed no obvious crystalline phase but became single phase of Ca7Mg7.25Si14 after heat treatment at 770 K under an atmospheric Ar with 5% -H2. As deposited film had a large power factor of 100 μW/(mK2) at 670 K. However, power factor decreased below 1 μW/(mK2) at 320-770K after the heat treatment at 770 K under an atmospheric Ar with 5% -H2.

A method for controlling the conduction-type in Mg2Si films without doping is investigated. Mg2Si films exhibit p-type conduction after a post-heat treatment up to 500 °C in atmospheric He. However, covering the films with Mg ribbon during a subsequent heat treatment at 500 °C converts the conduction to n-type, demonstrating that the heat treatment atmosphere can control the conduction type. Based on the reported first principles calculations suggesting that interstitial Mg and Mg vacancies in Mg2Si are the origins of n-type and p-type conduction, respectively, the post-heat treatment in He induces Mg vacancies due to the evaporation of Mg from the film, resulting in p-type conduction. The subsequent heat treatment when the film is covered with Mg ribbon fills the Mg vacancies and the additional interstitial Mg is incorporated, resulting in n-type conduction. These observations differ from the reported data for heat treatment of stable n-type conduction in non-doped Mg2Si-sintered bodies and may realize a novel control method for the conduction type in Mg2Si films.

Semiconducting iron disilicide (β-FeSi2) island grains of 50-100 nanometers in size were formed on the surface of Au-coated 3C-SiC powder by metal-organic chemical vapor deposition. On the surface of 3C-SiC powder, the Au-Si liquidus phase was obtained via a Au-Si eutectic reaction, which contributed to the formation of the β-FeSi2 island grains. This β-FeSi2/SiC composite powder could evolve hydrogen (H2) from methyl-alcohol aqueous solution under irradiation of visible light with wavelengths of 420-650 nm.

The Au-Si liquid phase was obtained by melting the Si surface via Au-Si eutectic reaction, which contributed to the formation of semiconducting iron disilicide (β-FeSi2), on Au-coated Si(100) substrates. By coating a substrate with an Au layer of 60 nm or more, the Au-Si liquid phase covered the entire Si substrate surface, and single-phase β-FeSi2 was grown on Si(100) substrates. A clear photoluminescence spectrum of β-FeSi2 indicated the formation of high-quality crystals with a low density of the non-radiative recombination center in the grains.

A RF magnetron sputtering method was used to prepare Mg2Si films at 300-400oC on (001) Al2O3 substrates from a Mg disc target with Si chips. Mg deposition was not detected at 400°C from a pure Mg disc target without Si chips due to the high vapor pressure of Mg. However, the amount of Mg deposition increased with the increase in Si/(Mg+Si) area ratio of the target surface together with the increase of the Si deposition. The obtained films had a stoichiometric composition of Si/(Mg+Si)=0.33 that consisted of the well crystalline Mg2Si single phase regardless of Si/(Mg+Si) area ratio of the target surface. This showed the existence of a “process window” against supply ratio of Si/(Mg+Si) for Mg2Si single phase films with a stoichiometric composition. This is considered to be due to the vaporization of the excess Mg prepared under the Mg excess condition as reported by Mahan et al. for Mg2Si films prepared at 200°C by ultra-high vacuum evaporation.

High-quality (010)-oriented epitaxial β-FeSi2 films were grown on Si(110) substrates by coating silver thin layer. The full width at half maximum of the rocking curve of β-FeSi2040 was 0.14o for the film deposited at 800°C on Si(110) substrates with 95 nm-thick silver layer. Moreover, this epitaxial β-FeSi2 film was constructed with single domain structure, and the lattice parameter of a-axis was extended by 0.7%. The photoluminescence spectrum from this epitaxial β-FeSi2 indicated that the band-gap was modulated by lattice strain of a-axis.

A clear PL spectrum was observed from β-FeSi2 grains on gold (Au)-coated (100)Si substrates, and indicated the formation of crystal with the same high quality level as the β-FeSi2 on a copper (Cu)-coated Si substrate. Moreover, the temperature dependence of photoluminescence peak intensities showed lower density of the nonradiative recombination center in β-FeSi2 grains on Au-coated Si substrates than that of β-FeSi2 film on Cu-coated Si. Au was not detected in β-FeSi2 grains by STEM-EDX observation, while Cu was observed in the grains and grain boundaries of β-FeSi2 and rolled as non-radiative recombination center.

A high-quality (100)-oriented epitaxial Fe3Si films were grown on (100) MgO substrates by RF-magnetron sputtering. The full width at half maximum of the Fe3Si 400 rocking curve was 0.18°, when the film was grown at 750°C. The epitaxial films of 100 nm thicknesses had a smooth continuous surface. The coercive field (Hc) was approximately 10 Oe, and the saturation magnetization (Ms) was 900 emu/cm3, which are almost the same as those of bulk Fe3Si. The anisotropy constant (K1) of magnetization indicated that the epitaxial Fe3Si films grown at 750°C mainly consisted of long range ordering phase (DO3 phase) and that the epitaxial films post-annealed at 900°C was constituted with ordering phase.

Iron silicide thin films were prepared on silicon (Si) and yittria-stabilized zirconia (YSZ) substrates using RF magnetron sputtering and evaporation methods. Epitaxial b-FeSi2 thin films were grown on (100) and (111) planes of Si and YSZ substrates, while noncrystallized films were deposited on (110) plane of both Si and YSZ substrates. The epitaxial relationships between the b-FeSi2 and YSZ were the same as those between b-FeSi2 and Si, in the case of (100) and (111) planes. It is possible that epitaxial b-FeSi2 film can be grown when substrates and b-FeSi2 surfaces consist of either a single element or only cations, while the crystalline film was not shown when either substrate or b-FeSi2 surface consists of a mixture of anions and cations or iron and silicon.

Iron silicide thin films were prepared on insulating substrates using RF magnetron sputtering method. Amorphous, polycrystalline and epitaxial β-FeSi2 were obtained on MgO(001), Al2O3(110) and Al2O3(001) substrates, respectively. Electrical conductivities of these films showed similar temperature dependence. Intrinsic band conduction and hopping conduction mechanism were predominant above and below 600K, respectively. The localized ordering in the polycrystalline and epitaxial films that controled the movement of carriers were as low as in the amorphous film. For the epitaxial β-FeSi2 film, electrical conductivity below 600K were affected by atomic ratio of silicon to iron (Si/Fe) in the films, because the localized ordering in the films decreased as Si/Fe atomic ratio decreased.

RuO2/(200-nm thick PZT)/RuO2 capacitors were prepared by MOCVD. RuO2 and PZT films were prepared at 350, and 395 and 445 °C from DER - O2 and Pb(C11H19O2)2 - Zr(O·t-C4H9)4 - Ti(O·i -C3H7)4 - O2 systems, respectively. Clear hysteresis loops originated to ferroelectricity was observed for the PZT films deposited at 445 °C but was not at 395 °C. However, by the addition of 10-nm thick Pt layer prepared on the RuO2 bottom electrode by e-beam evaporation, ferroelectricity above 30 μC/cm2 in remanent polarization (Pr) was obtained for the PZT films deposited at 395 °C. This shows that the existence of Pt layer improved the crystallinity of PZT phase. This capacitor shows hardly fatigue up to 1 × 1010 switching cycles, suggesting the fatigue free characteristics.