Universal Interface between Functional Oxides and Silicon

Integration of crystalline oxides with silicon provides a versatile platform to extend and advance silicon technology. The interface between oxide and Si controls the structure and functional properties of the resulting material. In particular, the formation of a submonolayer metal phase on silicon is the standard approach to stabilize the epitaxial growth of oxides. However, fundamental questions—a) whether the interface transforms in the process of the synthesis; and b) if it is possible to control the interface and its electronic structure by varying the submonolayer template—remain unanswered. The present study employs MBE synthesis of EuO and SrO on Si(001) to demonstrate that the structure of the oxide/Si interface does not depend on the type of the template, its symmetry, and stoichiometry. Chemical transformations of the templates converging into the same 2D product are detected in situ by electron diffraction. Then, the common interfacial structure of 1D periodicity is visualized by high-resolution electron microscopy. The study provides insights into the process of oxide integration with silicon but also sets the limits in designing oxide/Si interfaces.     

采用电子束检测技术辅助晶体管开发

涉足尖端技术研究工作的芯片制造商正在把无数新材料和奇特的器件结构结合起来,用于65nm及更低节点的量产。同时他们发现,在这些研究上的努力生产的结果还包括目前必须着手解决各器件各个层上出现的     

Photo‐Induced Functionalization of Spherical and Planar Surfaces via Caged Thioaldehyde End‐Functional Polymers

The synthesis and application of a novel reversible addition‐fragmentation chain transfer (RAFT) agent carrying a photocaged thioaldehyde moiety is described (λ_max = 355 nm). RAFT polymerization of styrene, dimethylacrylamide and a glycomonomer is evidenced (3600 g mol^?1 ≤ M_n ≤ 15 000 g mol^?1; 1.07 ≤ ? ≤ 1.20) with excellent end‐group fidelity. The photogenerated thioaldehyde on the chain ends can undergo hetero Diels–Alder reactions with dienes as well as reactions with nucleophiles. The terminal photoreactive polymers are photografted to porous diene‐reactive polymeric microspheres. The grafted particles are in‐depth characterized via scanning electron microscopy, elemental analysis, X‐ray photoelectron spectroscopy, and high resolution FT‐IR microscopy, leading to a qualitative as well as quantitative image of the core–shell objects. Grafting densities up to 0.10 molecules nm^?2 are reached. The versatility of the thioaldehyde ligation is evidenced by spatially resolved grafting of polystyrene onto nucleophilic groups present in poly (dopamine) (PDA)‐coated glass slides and silicon wafers via two‐photon direct laser writing (DLW) imaged by ToF‐SIMS. The combination of thioaldehyde ligation, RAFT polymerization, and DLW allows for the spatially resolved grafting of a vast range of polymers onto various substrates in any desired pattern with sub‐micrometer resolution.     

Layer-transfer process for silicon-on-insulator with improved manufacturability

We observe hydrogen platelet buildup in single-crystalline silicon caused by hydrogen-plasma processing. The platelets are aligned along a layer of lattice defects formed in silicon before the plasma processing. The buried-defect layer is formed by either silicon-into-silicon or argon-into-silicon implantation. We discuss the platelet nucleation, growth, and merge phenomena and discuss applicability of the plasma hydrogenation to silicon-on-insulator (SOI) wafer fabrication by layer transfer.     

Classification of rheumatoid joint inflammation based on laser imaging

We describe a classification system for a novel imaging method for arthritic finger joints. The basis of this system is a laser imaging technique which is sensitive to the optical characteristics of finger joint tissue. From the laser images acquired at baseline and follow-up, finger joints can automatically be classified according to whether the inflammatory status has improved or worsened. To perform the classification task, various linear and kernel-based systems were implemented and their performances were compared. Based on the results presented in this paper, we conclude that the laser-based imaging permits a reliable classification of pathological finger joints, making it a sensitive method for detecting arthritic changes.     

Design and analysis of UW-OFDM signals

Unique word-orthogonal frequency division multiplexing (UW-OFDM) is a novel signaling concept where the guard interval is implemented as a deterministic sequence, the so-called unique word. The UW is generated by introducing a certain level of redundancy in the frequency domain. Different data estimation strategies and the favourable bit error ratio (BER) performance of UW-OFDM, as well as comparisons to competing concepts have already extensively been discussed in previous papers. This work focuses on the different possibilities on how to generate UW-OFDM signals. The optimality of the two-step over the direct approach in systematic UW-OFDM is proved analytically, we present a heuristic algorithm that allows a fast numerical optimization of the redundant subcarrier positions, and we show that our original intuitive approach of spreading the redundant subcarriers in systematically encoded UW-OFDM by minimizing the mean redundant energy is practically also optimum w.r.t. transceiver based cost functions. Finally, we derive closed form approximations of the statistical symbol distributions on individual subcarriers as well as the redundant energy distribution and compare them with numerically found results.     

Strength properties and density of SO2 polluted spruce wood

2 pollution during approximately 1935 and 1992 respectively, was studied as to its mechanical properties (fracture toughness, acoustic emission (AE)) as well as its density and annual ring width changes. Earlywood and latewood width and density were measured with X-ray densitometry equipment. The mechanical tests were performed with specimens taken from the same trees using the wedge splitting technique. Using notched, rectangularly shaped specimens, the experiments allowed to determine the notch-tensile strength σ_NTS of each yearring in RL orientation separately by differentiating earlywood and latewood. The results show clear correlations between earlywood density and notch-tensile strength, good, inverse correlation to some extent between ring width and σ_NTS and also between AE emission activity and earlywood width for the less polluted trees. Data scattering with resulting less pronounced trends was found for all parameters measured for the more severely polluted trees. The results and correlations allow assuming that σ_NTS is influenced by the SO₂ pollution to some extent via treering growth (ring width) and density. The results point to a more pronounced influence of SO₂ pollution between approximately 1970 and 1985 than before that time, and a subsequent recovery of the tested wood properties in the trees that had survived this period.

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2 -belastet war, wurde auf seine mechanischen Eigenschaften und auf seine Dichte und Jahrringbreite hin untersucht. Früh- und Sp?tholzbreite und Dichte wurden mittels R?ntgendensitometrie, die mechanischen Eigenschaften mittels Keilspaltverfahren bestimmt. Durch die Verwendung von rechteckigen, gekerbten Proben lie? sich die Kerbzugfestigkeit σ_NTS jedes Jahrrings in RL-Orientierung bestimmen. Die Resultate zeigen einen klaren Zusammenhang zwischen Frühholzdichte und Kerbzugfestigkeit sowie einen gewissen inversen Zusammenhang zwischen Jahrringbreite und Kerbzugfestigkeit bzw. Schallemissionsaktivit?t und Frühholzbreite für die wenig gesch?digten B?ume. Bei den st?rker gesch?digten B?umen war die Streuung der Me?werte deutlich h?her und die Abh?ngigkeiten schw?cher ausgepr?gt. Die Resultate und Zusammenh?nge deuten darauf hin, da? die Kerbzugfestigkeit durch die SO₂ Belastung über den Jahrringwuchs (Jahrringbreite) und die Dichte beeinflu?t wird. Die Resultate zeigen einen st?rkeren Einflu? der SO₂ Belastung zwischen 1970 und 1985 und deuten auf eine Erholung in den Holzeigenschaften bei jenen B?umen, die diese Periode überlebt haben, hin.

     

Self‐Healing Reduced Graphene Oxide Films by Supersonic Kinetic Spraying

The industrial scale application of graphene and other functional materials in the field of electronics has been limited by inherent defects, and the lack of simple deposition methods. A simple spray deposition method is developed that uses a supersonic air jet for a commercially available reduced graphene oxide (r‐GO) suspension. The r‐GO flakes are used as received, which are pre‐annealed and pre‐hydrazine‐treated, and do not undergo any post‐treatment. A part of the considerable kinetic energy of the r‐GO flakes entrained by the supersonic jet is used in stretching the flakes upon impact with the substrate. The resulting “frozen elastic strains” heal the defects (topological defects, namely Stone‐Wales defect and C₂ vacancies) in the r‐GO flakes, which is reflected in the reduced ratio of the intensities of the D and G bands in the deposited film. The defects can also be regenerated by annealing.     

Conducting Domain Walls in Lithium Niobate Single Crystals

Ferroic materials play an increasingly important role in novel (nano)electronic devices. Recently, research on domain walls (DWs) receives a big boost by the discovery of DW conductivity (DWC) in BiFeO₃ and Pb(Zr_xTi_1‐x)O₃ ferroic thin films. Here, it is demonstrated that DWC is not restricted to thin films, but equally applies to millimeter‐thick wide‐bandgap, ferroic single crystals, such as LiNbO₃. In this material transport along DWs can be switched by super‐bandgap illumination and tuned by engineering the tilting angle of DWs with respect to the polar axis. The results are consistently obtained using conductive atomic force microscopy to locally map the DWC and macroscopic contacts, thereby in addition investigating the temperature dependence, DW transport activation energies, and relaxation behavior.