Ge 2 Sb 2 Te 5 thin film is a promising candidate for recording material of phase-change optical disks, and nitrogen is doped into this film to increase overwrite characteristics. In this study, the crystal structure and the microstructure of nitrogen-doped Ge 2 Sb 2 Te 5 thin film were investigated. In the annealed nitrogen-doped thin film, the characteristic face-centered cubic peaks on the X-ray diffraction pattern were broadened and shifted to a smaller angle with the increase of nitrogen content. In addition, a remarkably reduced grain size and a highly strained structure are seen in the transmission electron microscopy image. Doped nitrogen in Ge 2 Sb 2 Te 5 thin film plays two roles. One is to distort the crystal lattice and induce a strain field in the film. The other is to refine the grain size of the film through precipitation. The crystal lattice is transformed from face-centered cubic to a hexagonal structure in nitrogen content above 20 at.%.

The crystallization behavior of amorphous Ge2Sb2Te5 thin films were investigated by using differential scanning calorimetry, x-ray diffraction, and optical reflectivity measurements. The analysis of in situ ellipsometry isotherm Ge2Sb2Te5 films based on the Johnson–Mehl–Avrami equation revealed that the crystallization process near 150 °C was a two-step process. In this alloy thin film, the kinetic exponents in the Johnson–Mehl–Avrami equation were about 4.4 for the first stage and 1.1 for the second stage. A kinetic model based on the cascaded crystallization is proposed. The proposed model showed good agreement with the experimental results obtained by transmission electron microscopy and x-ray diffraction.

An oxygen-doped GeSbTe interface layer improves the overwriting characteristics of the phase-change optical disk in the blue wavelength. The thermal and optical properties of oxygen-doped GeSbTe film and its crystal structure were investigated. Crystallization temperature and activation energy of the amorphous Ge–Sb–Te–O films are increased with the oxygen concentration while the melting point is decreased. The refractive index of the crystalline state monotonically increases with the oxygen concentration of the film, while its extinction coefficient monotonically decreases. In terms of the crystalline structure, fcc characteristic peaks disappear gradually with oxygen concentration, and above 35 at.% of oxygen, hexagonal peaks appear.

Microstructural control in thin-layer multilayer ceramic capacitors (MLCC) is one of the present day challenges to maintain an increase in capacitive volumetric efficiency. This present paper opens a series of investigations aimed to engineer the stability of ultra-thin Ni electrodes in BaTiO 3 -based multilayer capacitors using refractory metal additions to Ni. Here, pure Ni and Ni-1 wt.% Cr alloy powders are used to produce 0805-type BME MLCCs with 300 active layers and with dielectric and electrode layer thickness around 1 μm. To investigate the continuity of Ni electrodes, both MLCC chips with pure and doped electrodes were sintered at different temperatures for 5 h. It is found that the continuity of Ni electrodes is improved most likely due to the effect of Cr on the lowmelting point (Ni,Ba,Ti) interfacial alloy layer formation. The interfacial alloy layer is not observed when Cr is segregated at Ni-BaTiO 3 interface in the Cr-doped samples, while it is found in all undoped samples. The interfacial alloy layer is believed to increase mass-transfer along the Ni-BaTiO 3 interfaces facilitating an acceleration of Ni electrodes discontinuities.

Multilayer ceramic capacitors based on BaTiO 3 dielectric compositions and Ni inner electrodes have complex interfacial reactions that impact the continuity of the inner electrode microstructure. Previously we demonstrated that through the addition of Cr to Ni, a significant improvement in the continuity of ultra-thin Ni electrodes in Ni-BaTiO 3 multilayer capacitors could be achieved. Here, the effect of the Cr addition to the nickel electrode pastes is studied with regard to the electrical properties. Low-field electrical measurements demonstrate no major differences between Cr doped Ni and undoped Ni. However, high-field measurements show a significant decrease to the total capacitor resistance. Under a critical electrical bias the conductivity significantly increases due to a FowlerNordheim tunneling conduction though the interfacial Schottky barrier at the dielectric-electrode interface; the onset voltage of this conduction is much lower than with the undoped nickel. Based on these results, we evaluate criteria for the selection of an appropriate refractory metal in order to improve the Ni electrode continuity.