We trace Sn nanoparticles (NPs) produced from SnO2 nanotubes (NTs) during lithiation initialized by high energy e-beam irradiation. The growth dynamics of Sn NPs is visualized in liquid electrolytes by graphene liquid cell transmission electron microscopy. The observation reveals that Sn NPs grow on the surface of SnO2 NTs via coalescence and the final shape of agglomerated NPs is governed by surface energy of the Sn NPs and the interfacial energy between Sn NPs and SnO2 NTs. Our result will likely benefit more rational material design of the ideal interface for facile ion insertion.

We demonstrate the tungsten disulfide (WS2) thin film catalysts prepared by the sulfurization of vacuum deposited WO3 thin films for efficient hydrogen production with over 90% Faradaic efficiency. The 23-nm-thick WS2 thin film catalyst heterojunction with p-type silicon photocathode could exhibit a photocurrent density of 8.3 mA/cm2 at 0 V versus a reversible hydrogen electrode (RHE), a low onset potential of 0.2 V versus RHE when photocurrent density reaches −1 mA/cm2 and long-term stability over 10 h. The enhanced catalytic activities of WS2/p-Si photocathodes compared with the bare p-Si photocathode originate from a number of edge sites in the synthesized polycrystalline thin films, which could act as hydrogen evolution catalyst.

Background: The influences of demographics, culture, language, and environmental changes on Mini-Mental State Examination (MMSE) scores are considerable.

Methods: Using a sample of 7452 healthy, community-dwelling elderly Koreans, aged 55 to 94 years, who participated in the four ongoing geriatric cohorts in Korea, we investigated demographic influences on MMSE scores and derived normative data for this population. Geropsychiatrists strictly excluded subjects with cognitive disorders according to the protocol of the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet (CERAD-K) Clinical Assessment Battery (CERAD-K-C).

Results: Education (standardized β = 0.463), age (standardized β = −0.303), and gender (standardized β = −0.057) had significant effects on MMSE scores (p < 0.001). The score of MMSE increase 0.379 point per 1-year education, decrease 0.188 per 1-year older, and decrease 0.491 in women compared to men. Education explained 30.4% of the scores’ total variance, which was much larger than the variances explained by age (8.4%) or gender (0.3%). Accordingly, we present normative data for the MMSE stratified by education (0, 1–3, 4–6, 7–9, 10–12, and ≥ 13 years), age (60–69, 70–79, and 80–89 years), and gender.

Conclusions: We provide contemporary education-, age-, and gender-stratified norms for the MMSE, derived from a large, community-dwelling elderly Korean population sample, which could be useful in evaluating individual MMSE scores.

Due to a rapid shrinkage in memory devices, backned of the line process experiences great difficulties, especially Al metallization. Furthermore, there is a continuous demands in low line resistance in order to promote device performances. In this article, Al damascene process is proposed as compared to Al patterning process, which suffers from inherent pattering issue at a fine pitch under 70nm. The most difficulties in the development of Al damascene process were to form a stable and void free Al in fine trench and to obtain scratch and corrosions free Al surface. In this study, 50nm beyond fill was successfully achieved by “bottom up growth” of CVD Al. For the process, CVD Al by using Methylpyrroridine Alane (MPA) precursor was deposited on a stacked film of CVD TiN and PVD TiN as a wetting layer, which was followed by PVD Al and reflow, then the Al surface was polished with colloidal silica based slurry.

In addition, electrical property of Al scheme and W scheme was compared with damascene pattern, along with which we demonstrated that around 36% decrease in parasitic capacitance is achievable by decrease of metal line height from 3500A to 1000A on simulation test implying that device performance could be enhanced.

BaxSr1−xTiO3 (BST, x=0.5 and 0.6) thin films have been deposited onto (100) MgO single crystal substrates by pulsed laser deposition (PLD). The room temperature capacitance and dielectric quality factor (Q=1/tanδ have been measured as a function of electric field (≤ 100 kV/cm) at microwave frequencies (1 to 20 GHz) using silver interdigitated electrodes deposited on top of the BST film. It has been observed that the dielectric constant of the film and its change with electric field are closely related to film phase (amorphous to crystalline phase) and film strain which affects the ionic polarization of the film. Amorphous BST films show high dielectric Q (> 100) with low dielectric constant (∼30–200) and low dielectric tuning (< 1%), presumably due to small ionic polarization. Crystalline films have a higher dielectric constant (∼1000–3000) and a higher dielectric tuning (∼ 65%) but a lower dielectric Q (∼20). As an optimal microstructure of the film for tunable microwave applications, strain-relieved large-grained (∼5000 Å) randomly oriented polycrystalline films were deposited using a thin amorphous buffer layer of BST (∼50 Å). Very large grains (size up to a few microns) were observed in BST films prepared using a thicker amorphous buffer layer (∼500 Å). We will present results on how careful control of microstructure can lead to films with optimal dielectric properties for the tunable microwave devices.

Single phase BaxSr1−xTiO3 (BST) films (∼0.5-7 μm thick) have been deposited onto single crystal substrates (MgO, LaAlO3, SrTiO3) by pulsed laser deposition. Silver interdigitated electrodes were deposited on top of the ferroelectric film. The room temperature capacitance and dielectric Q (1/tanδ) of the film have been measured as a function of electric field (≤80 kV/cm) at 1 - 20 GHz. The dielectric properties of the film are observed to strongly depend on substrate type and post-deposition processing. After annealing (≤1000° C), it was observed that the dielectric constant and % tuning decreased and the dielectric Q increased for films deposited onto MgO, and the opposite effect was observed for films deposited onto LaA1O3. Presumably, this change in dielectric properties is due to the changes in film stress. Very thin (∼50 Å) amorphous BST films were successfully used as a stress-relief layer for the subsequently deposited crystalline BST (∼5000 Å) films to maximize % tuning and dielectric Q. Films have been deposited from stoichiometric targets and targets that have excess Ba and Sr. The additional Ba and Sr has been added to the target to compensate for deficiencies in Ba and Sr observed in the deposited BST (x=0.5) films. Films deposited from compensated targets have higher dielectric constants than films deposited from stoichiometric targets. Donor/acceptor dopants have also been added to the BST target (Mn, W, Fe ≤4 mol.%) to further improve the dielectric properties. The relationship between the dielectric constant, the dielectric Q, the change in dielectric constant with electric field is discussed.

Single phase BaxSr1−xTiO3 (x=0.5 and 0.6) thin films (∼5000Å thick) have been deposited onto (100) MgO single crystal substrate with (Ba,Sr) compensated and/or (Mn,Fe,W) doped targets using pulsed laser deposition (PLD). The room temperature capacitance (C) and dielectric Q (1/tanδ) have been measured at microwave frequencies of I to 20 GHz as a function of electric field (0-80kV/cm). Microstructural defects associated with cation and anion vacancies have been observed in BaxSr1−xTiO3 films. Compensation of the ablation target with excess Ba and Sr tends to increase the dielectric constant and the dielectric Q. A film deposited with (Ba,Sr) compensated target has been obtained with 25% tuning, where % tuning is defined as {(C(0)-C(E))/C(O))×100, and dielectric Q of ∼ 100 at room temperature (1 — 10 GHz) for DC bias field (E=67 kV/cm). A further increase in the dielectric Q is observed by the addition of donor/acceptor dopants such as Mn, Fe, and W (Q≈100-240). The effects of (Ba, Sr) compensation and (Mn,Fe,W) doping on the film structure and dielectric properties are discussed.

During the plasma etching of Al-Si-Cu alloy used as a metal interconnection, it is generally reported that the metal pillar (or conical residue) affecting the degradation of device yield is formed by the micromasking effect of copper compound. However, it is stilldisputed with the formation mechanism and composition of the micromasking material. Moreover, the elimination method of the metal pillar is not well known.

According to previous reports, it is argued that the micromasking material consists of Cu agglomerates, A12Cu, or CuC1, and the formation mechanism of the micromasking is due to byproduct during plasma etching or reaction product during metal depositionor etching. However, using scanning electron microscopy (SEM), energy dispersive of x-ray (EDX), and high resolution Auger spectroscopy (HRAES), it is newly found that the micromasking consists of three layered structure, that is copper aluminum oxide, A12Cu, and Cu agglomerates. These results are quite different from previous reports. In addition, the removal methods of the metal pillar are suggested, which are high power dry etch process and multilayered metal deposition.