Distribution of wax in laser printer toner was observed using an ultra-high-voltage (UHV) and a medium-voltage transmission electron microscope (TEM). As the radius of the wax spans a hundred to greater than a thousand nanometers, its three-dimensional recognition via TEM requires large depth of focus (DOF) for a volumetric specimen. A tomogram with a series of the captured images would allow the determination of their spatial distribution. In this study, bright-field (BF) images acquired with UHV-TEM at a high tilt angle prevented the construction of the tomogram. Conversely, the Z-contrast images acquired by the medium-voltage TEM produced a successful tomogram. The spatial resolution for both is discussed, illustrating that the image degradation was primarily caused by beam divergence of the Z-contrast image and the combination of DOF and chromatic aberration of the BF image from the UHV-TEM.

The formation and morphological evolution of germanides formed in a ternary Ni/Ta-interlayer/Ge system were examined by ex situ and in situ annealing experiments. The Ni germanide film formed in the Ni/Ta-interlayer/Ge system maintained continuity up to 550°C, whereas agglomeration of the Ni germanide occurred in the Ni/Ge system without Ta-interlayer. Through microstructural and chemical analysis of the Ni/Ta-interlayer/Ge system during and after in situ annealing in a transmission electron microscope, it was confirmed that the Ta atoms remained uniformly on the top of the newly formed Ni germanide layer during the diffusion reaction. Consequently, the agglomeration of the Ni germanide film was retarded and the thermal stability was improved by the Ta incorporation.

The oxidation mechanism and thermal stability of nickel oxide (NiO)/carbon nanotube (CNT) composites were investigated by examining composites with different NiO contents by thermogravimetric analysis and transmission electron microscopy (TEM). NiO acts as a catalyst in the oxidation of CNT in the composite. CNTs can be oxidized, even in a vacuum, by reducing NiO to nickel at temperatures lower than the normal oxidation temperature of CNTs. This phase transition was confirmed directly by in situ heating TEM observations. In air, reduction by CNT occurs simultaneously with reoxidation by gaseous O2 molecules, and NiO maintains its phase. The thermal stability decreased with increasing NiO content because of defects in the CNT generated by the NiO loading.

Thin-film transistors (TFTs) utilizing a TiZnSnO (TZTO) channel layer were fabricated by using a solution process. The effect of annealing temperature on the device performance of the TZTO TFTs was investigated. TFTs with nanocrystalline TZTO films exhibited a better device performance than those with amorphous TZTO films. The on/off current ratio of the TZTO TFTs annealed at 600 °C was as large as 4.2 × 106. The field-effect mobility (μFE) of 4.1 cm2/Vs and subthreshold swing of 1.2 V/decade were achieved.

Evaluation of apoptosis and expression level of apoptosis-related genes is useful for examining the variation in embryo quality according to environmental change. The objective of this study was to investigate DNA fragmentation and apoptosis-related gene expression patterns in frozen-thawed bovine blastocysts. In vitro produced day 7 blastocysts were frozen by two different vitrification methods (conventional 0.25 ml straw or MVC straw). After thawing, DNA fragmentation of surviving embryos was examined by TUNEL assay, and the expression patterns of their apoptotic genes (survivin, Fas, Hsp 70 and caspase-3) were evaluated using real-time quantitative reverse transcriptase polymerase chain reaction. In vitro survival rates of frozen-thawed embryos were higher following the MVC vitrification method (88.2% re-expanded at 24 h, 77.1% hatching at 48 h) than the conventional (C) vitrification method (77.0% re-expanded at 24 h, 66.7% hatching at 48 h). However, both vitrified methods resulted in a significantly higher apoptotic index (C vitrification method 11.9%, MVC vitrification method 11.0%) than in non-frozen embryos (3.0%). Expression levels of survivin, Fas, caspase-3, and Hsp 70 were also increased in the frozen-thawed embryos compared with non-frozen embryos. These results indicate that the cryopreservation procedure might cause damage that results in an increase in DNA fragmentation and apoptosis-related gene transcription, reducing developmental capacity of frozen-thawed embryos.

The barrier metal properties of Plasma Enhanced ALD (PEALD) TaN deposited on low-k dielectric film (SiCOH) with a k value of 3.0 at a deposition temperature of 300°C by using pentakis (ethylmethylamino) tantalum (PEMAT) and various plasma gases was investigated. The film resistivity of TaN is about 1000 μΩ.cm under the plasma power of 200 W and the frequency of 400 KHz, respectively. The resistivity was significantly reduced by approximately 360 μΩ.cm for the optimized condition of 300 W and 13.56 MHz. In addition, good uniformity was obtained by applying two-step plasma treatment process. The film thickness per cycl of the TaN using two-step plasma was decreased from 1.0 Å to 0.65 Å by reducing a base pressure, indicating the increase of the film density. The PEALD TaN with almost 100% coverage in this paper's dual damascene structure has a contact resistance of about 1.6 Ω /chain at via size of 0.19um.

We have developed a simple and fast methodology to control the orientation of cylindrical microdomains in thin block copolymer films under controlled atmosphere conditions. Asymmetric block copolymers of polystyrene and poly(ethylene oxide) (PS-b-PEO) were dissolved in toluene and spin coated with less than one minute exposure to different solvent vapors and controlled humidity. The specific choice of solvents was based on the polymer solubility parameters and the solvent vapor pressure. By controlling the spin coating environment we were able to produce cylinders with orientations ranging from parallel to perpendicular with respect to the substrate. Orientation was apparently controlled by the preferential affinity of the vapor atmosphere. A combinatorial gradient technique was employed to investigate the mechanism of solvent-induced microdomain orientation.

Ultramicrotomy, the technique of cutting nanometers-thin slices of material using a diamond knife, was applied to prepare transmission electron microscope (TEM) specimens of nanoporous poly(methylsilsesquioxane) (PMSSQ) thin films. This technique was compared to focused ion beam (FIB) cross-section preparation to address possible artifacts resulting from deformation of nanoporous microstructure during the sample preparation. It was found that ultramicrotomy is a successful TEM specimen preparation method for nanoporous PMSSQ thin films when combined with low-energy ion milling as a final step. A thick, sacrificial carbon coating was identified as a method of reducing defects from the FIB process which included film shrinkage and pore deformation.

Pt thin films of various thicknesses (30 nm ∼ 200 nm) were deposited on Si wafers with SiO2, Ti, TiO2, or IrO2 buffer layers at various temperatures (room temperature ∼200 °C) by a direct current magnetron sputtering process. The Pt films showed a strong (111)-preferred texture irrespective of the thickness, under-layer, and growth temperature. The authors previously reported [J-E. Lim, D-Y. Park, J.K. Jeong, G. Darlinski, H.J. Kim, and C.S. Hwang, Appl. Phys. Lett. 81, 3224 (2002)] that the films were composed of three kinds of grains with slightly different (111) lattice parameters (bulklike, 1.0% and 2.1% larger). This study details the microstructural variations of the Pt films according to the variations of experimental parameters. The different deposition conditions produced slightly different crystalline structures, but the three different (111) lattice parameters were always found. Epitaxial (200) Pt films on a (200) MgO substrate and a highly (111) textured Au thin film on a SiO2/Si did not show the same splitting in the lattice parameter. The grains with 1.0% and 2.1% larger (111) lattice parameter almost disappeared after postannealing at 1000 °C. However, surface chemical binding of the Pt film before and after annealing was unchanged. Therefore, it is believed that the lattice parameter splitting in the (111) textured Pt film originated from the interfacial grains with the distorted crystal structure due probably to growth stress.

We investigated the photoluminescence as well as the crystal structure and optical energy gaps of the Zn1-xCdxAl2Se4-4xS4x solid solution system based on the Al-related compounds of ZnAl2Se4, ZnAl2S4, CdAl2Se4, and CdAl2S4. The single crystals of the system with 0.0 ≤ x ≤ 1.0 were grown by the chemical transport reaction technique. The Zn1-xCdxAl2Se4-4xS4x crystallizes in a defect chalcopyrite structure for a whole composition and has an optical energy gap ranging from 3.525 to 3.577 eV at 13 K. The photoluminescence spectra at 13 K showed a strong emission band in the blue spectral region and a weak broad emission band in the visible region due to donor–acceptor pair recombination. The composition and temperature dependence of these bands were examined in the investigated regions. The simple energy band scheme for the radiative mechanisms of the Zn1-xCdxAl2Se4-4xS4x is proposed on the basis of our experimental results along with photo-induced current transient spectroscopy measurements.

We have investigated surface treatment effect on the interfacial reaction of Pd/p-GaN interface and also room temperature ohmic contact formation mechanism of Pd-based ohmic contact. In order to examine room temperature ohmic behavior, various metal contact systems were deposited and current-voltage measurements were carried out. In spite of large theoretical Schottky barrier height between Pd and p-GaN, Pd-based contact showed perfect ohmic characteristic even before annealing. According to the results of synchrotron X-ray radiation, the closed-packed atomic planes (111) of the Pd film were quite well ordered in surface normal direction as well as in the in-plane direction. The effective Schottky barrier height of Au/Pd/Mg/Pd/p-GaN was 0.47eV, which was estimated by Norde method. This discrepancy between theoretical barrier height and the measured one might be due to the epitaxial growth of Pd contact metal and so the room-temperature ohmic characteristic of Pd-based ohmic contact was related strongly to the in-plane epitaxial quality of metal on p-GaN.

A gradual change in thermal oxide surface state from hydrophilic to hydrophobic was observed with time -delay in a clean room environment. Surface quality and reflectivity for the Al/Ti metal layers showed a strong dependency on the oxide surface state. From the hydrophilic oxide substrate, a lower (002) Ti preferred orientation was obtained than from hydrophobic ones. This resulted in a degraded (111) Al preferred orientation and rough metal surface. The RF-etch process increased the smoothness and hydrophobic surface property for the inter -metal dielectric (IMD) oxides, and therefore greatly improved Al/Ti surface quality. When conventional CMOS double layer metal interconnection process is performed, metal inter-line bridge yield was strongly affected by the surface state of substrate oxides.

Basic mechanisms for both Ni- and Pd-metal induced lateral crystallization (MILC) are investigated. For both cases, tiny silicides were formed under the metal deposited area, and propagated toward amorphous Si films leaving crystallized Si behind at temperatures as low as 500 °C. Ni-MILC was influenced by Pd such that the lateral crystallization rate was enhanced, and the temperature for the lateral crystallization was lowered to 450 °C. Through TEM analysis and external stress experiments, it was found that the enhancement of the lateral crystallization rate was closely related to the compressive stress generated by the formation of nearby Pd2Si.

The microstructure of Cu thin films in various deposition conditions and the influence of their microstructure on the adhesion strength between Cu/Cr films and polyimides were studied. Cr films (50 nm thick) and Cu films (500 or 1000 nm thick) were deposited on polyimide films by DC magnetron sputtering. The Ar pressure during Cu deposition was controlled to 5, 50, and 100 mtorr. The microstructure was characterized using SEM and TEM. The adhesion strength between Cu/Cr and polyimide was measured using a modified Tpeel test. Plastic deformation of the peeled metal was qualitatively measured using the XRD technique. The Cu film sputtered at 5 mtorr has a dense and uniform structure, while lowdensity regions or open boundaries between columns exist in the film deposited at higher pressure. As sputtering pressure increases, open boundaries are observed more frequently. The peel adhesion strength of Cr film to polyimide increases with Cu sputtering pressure. The adhesion change of Cu/Cr film can be interpreted as the difference in plastic deformation. Open boundaries in the Cu film seem to play an important role in increasing the amount of plastic deformation in the metal film during peeling.