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Ionic effects on the transport characteristics of nanowire-based FETs in a liquid environment

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Nano Research 2014年第3期7卷 380-389页

作者： Daijiro Nozaki Jens Kunstmann Felix Zorgiebel Sebastian Pregl Larysa Baraban walter m. weber Thomas mikolajick Gianaurelio Cuniberti Institute for materials Science and max Bergmann Center of Biomaterials TU Dresden 01062 Dresden Germany Department of Chemistry Columbia University 3000 Broadeway New York NY 10027 USA Namlab gGmbH N6thinger Str. 64 01187 Dresden Center forAdvancing Electronics Dresden (cfAED) TU Dresden 01062 Dresden Germany Dresden Center for Computational materials Science (DCCmS) TU Dresden 01062 Dresden Germany

For the development of ultra-sensitive electrical bio/chemical sensors based on nanowire field effect transistors （FETs）, the influence of the ions in the solution on the electron transport has to be understood. For this purpose we establish a simulation platform for nanowire FETs in the liquid environment by implementing the modified Poisson-Boltzmann model into Landauer transport theory. We investigate the changes of the electric potential and the transport characteristics due to the ions. The reduction of sensitivity of the sensors due to the screening effect from the electrolyte could be successfully reproduced. We also fabricated silicon nanowire Schottky-barrier FETs and our model could capture the observed reduction of the current with increasing ionic concentration. This shows that our simulation platform can be used to interpret ongoing experiments, to design nanowire FETs, and it also gives insight into controversial issues such as whether ions in the buffer solution affect the transport characteristics or not.

关键词： nanowire field effecttransistors (FETs) biosensors silicon nanowires Poisson-Boltzmann theory Landauer model

Parallel arrays of Schottky barrier nanowire field effect transistors： Nanoscopic effects for macroscopic current output

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Nano Research 2013年第6期6卷 381-388页

作者： Sebastian Pregl walter m. weber Daijiro Nozaki Jens Kunstmann Larysa Baraban Joerg Opitz Thomas mikolajick Gianaurelio Cuniberti Institute for materials Science and max Bergmann Center of Biomaterials TU Dresden Dresden 01062 Germany NamLab GmbH Dresden 01187 Germany Fraunhofer Institute IZFP Dresden Dresden 01109 Germany Institute for Semiconductors and microsystems Technology TU Dresden Dresden 01187 Germany Division of IT Convergence Engineering POSTECH Pohang Korea

We present novel Schottky barrier field effect transistors consisting of a parallel array of bottom-up grown silicon nanowires that are able to deliver high current outputs. Axial silicidation of the nanowires is used to create defined Schottky junctions leading to on/off current ratios of up to 106. The device concept leverages the unique transport properties of nanoscale junctions to boost device performance for macroscopic applications. Using parallel arrays, on-currents of over 500 gA at a source-drain voltage of 0.5 V can be achieved. The transconductance is thus increased significantly while maintaining the transfer characteristics of single nanowire devices. By incorporating several hundred nanowires into the parallel arra36 the yield of functioning transistors is dramatically increased and device- to-device variability is reduced compared to single devices. This new nanowire- based platform provides sufficient current output to be employed as a transducer for biosensors or a driving stage for organic light-emitting diodes （LEDs）, while the bottom-up nature of the fabrication procedure means it can provide building blocks for novel printable electronic devices.

关键词： silicon nanowire effective Schottky barrier lowering parallel arra^electric field enhancement output current amplification

Optoelectronic switching of nanowire-based hybrid organic/oxide/semiconductor field-effect transistors

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Nano Research 2015年第4期8卷 1229-1240页

作者： Eunhye Baek Sebastian Pregl mehrdad Shaygan Lotta Romhildt walter m. weber Thomas mikolajick DmitryA. Ryndyk Larysa Baraban Gianaurelio Cuniberti Institute for materials Science and max Bergmann Center of Biomaterials TU Dresden 01062 Dresden Germany Center for Advancing Electronics Dresden TU Dresden 01062 Dresden Germany Division of IT Convergence Engineering Pohang University of Science and Technology Pohang Korea NamLab GmbH Nothnitzer Strasse 64 01187 Dresden Germany Dresden Center for Computational materials Science TU Dresden 01062 Dresden Germany

A novel photosensitive hybrid field-effect transistor （FET） which consists of a multiple-shell of organic porphyrin film/oxide/silicon nanowires is presented. Due to the oxide shell around the nanowires, photoswitching of the current in the hybrid nanodevices is guided by the electric field effect, induced by charge redistribution within the organic film. This principle is an alternative to a photoinduced electron injection, valid for devices relying on direct junctions between organic molecules and metals or semiconductors. The switching dynamics of the hybrid nanodevices upon violet light illumination is investigated and a strong dependence on the thickness of the porphyrin film wrapping the nanowires is found. Furthermore, the thickness of the organic films is found to be a crucial parameter also for the switching efficiency of the nanowire FET, represented by the ratio of currents under light illumination （ON） and in dark conditions （OFF）. We suggest a simple model of porphyrin film charging to explain the optoelectronic behavior of nanowire FETs mediated by organic film/oxide/semiconductor junctions.

关键词： hybrid nanoelectronics silicon nanowirefield-effect transistors porphyrin optoelectronic switching organic/oxide/semiconductor junctions

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上部地壳的流体作用与大理岩的低温塑性

岩石学报 2000年第4期16卷 499-505页

作者：刘俊来 weber K walter J 吉林大学地球科学系长春130061 格廷根大学岩石圈地质与动力学研究所

本文应用光学显微镜、透射电子显微镜和阴极发光显微镜系统研究了 Waterberg断层带 (纳米比亚 )内粗晶大理岩中发育的构造岩。宏观碎裂结构与微观糜棱状结构是断层构造岩的主要特点。巨大的变形碎屑与弥漫的细小颗粒基质形成了鲜明的反... 详细信息

本文应用光学显微镜、透射电子显微镜和阴极发光显微镜系统研究了 Waterberg断层带 (纳米比亚 )内粗晶大理岩中发育的构造岩。宏观碎裂结构与微观糜棱状结构是断层构造岩的主要特点。巨大的变形碎屑与弥漫的细小颗粒基质形成了鲜明的反差。广泛发育的压溶缝合线与多阶段方解石细脉遍布构造带不同部位。TEm亚微分析表明 ,细粒基质是由粗大碎屑经过亚颗粒旋转 ,并伴随着局部颗粒边界迁移形成的动态重结晶颗粒。虽然亚颗粒粒度具有简单的峰值分布 (～ 0 .3～0 .4μm) ,但动态重结晶颗粒的粒度却具有较大的变化范围 (0 .1～ 3.0μm )并具有多峰值分布的趋势。 TEm亚微结构 (晶格位错结构 )分析与亚颗粒、动态重结晶粒度、变形双晶宽度统计分析充分证明变形—恢复过程的非稳态特点。结合阴极发光分析阐明在上部地壳环境中 ,方解石大理岩经历脆性变形过程中 ,流体相广泛介入到变形作用中 ,并促进岩石的非稳态脆 -韧性转变与低温塑性的出现。

关键词：低温塑性水解弱化大理岩流体作用脆性变形

The Leaf Reticulate mutant dovl Is Impaired in the First Step of Purine metabolism

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molecular Plant 2012年第6期5卷 1227-1241页

作者： Christian Rosar Kerstin Kanonenberg Arun m. Nanda michael mielewczik Andrea Brautigam Ondrej Novake miroslav Strnad Achim walter Andreas Rm. weber Institute for Plant Biochemistry Heinrich-Heine-Universitat Universitatsstrasse 1 D-40225 Dusseldorf Germany Present address: Institute of Bio- and Geosciences IBG-1: Biotechnology Forschungszentrum Julich D-52425 Julich Germany Institute of Bio- and Geosciences IBG-2: Plant Sciences Forschungszentrum Julich D-52425 Julich Germany Present address: Institute of Agricultural Sciences Universitatstrasse 2 ETH Zurich CH-8092 Zurich Switzerland Laboratory of Growth Regulators Palacky University & Institute of Experimental Botany AS CR Slechtitelu 11 CZ-78371 Olomouc Czech Republic

A series of reticulated Arabidopsis thaliana mutants were previously described. All mutants show a reticulate leaf pattern, namely green veins on a pale leaf lamina. They have an aberrant mesophyll structure but an intact layer of bundle sheath cells around the veins. Here, we unravel the function of the previously described reticulated EmS-mutant dovl （differential development of vascular associated cells 1）. By positional cloning, we identified the mutated gene, which encodes glutamine phosphoribosyl pyrophosphate aminotransferase 2 （ATase2）, an enzyme catalyzing the first step of purine nucleotide biosynthesis, dovl is allelic to the previously characterized cial-2 mutant that was isolated in a screen for mutants with impaired chloroplast protein import. We show that purine-derived total cytokinins are lowered in clovl and crosses with phytohormone reporter lines revealed differential reporter activity patterns in dovl. metabolite profiling unraveled that amino acids that are involved in purine biosynthesis are increased in dovl. This study identified the mo- lecular basis of an established mutant line, which has the potential for further investigation of the interaction between metabolism and leaf development.

关键词： leaf development reticulated mutants cytokinin growth kinetics purine metabolism.

Phylogenetic relationships of five genera of Xylariales and Rosasphaeria ***.(Hypocreales)

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Fungal Diversity 2012年第1期52卷 75-98页

作者： walter m.Jaklitsch Hermann Voglmayr Department of Systematic and Evolutionary Botany Faculty Centre of BiodiversityUniversity of ViennaRennweg 141030 WienAustria

Eight inconspicuous non-stromatic perithecial fungi immersed in plant tissue are assessed with respect to their morphology,ecology and phylogenetic *** is laid on two genera now and then placed in the family Hyponectriaceae,Xylariales:Leiosphaerella with its type species *** occurring on Vaccinium,and Pseudomassaria with its type species *** occurring on *** molecular phylogenetic analyses of LSU and ITS sequences,the generic types of these genera are closely related,but their familial affiliation within Xylariales remains *** sepincoliformis clusters with ***,whereas *** is not congeneric with Pseudomassaria and *** is combined in Leiosphaerella despite its *** species thought to belong to Leiosphaerella are re-assessed:*** that occurs on Rosa,is disposed in the new genus Rosasphaeria,which is close to Eucasphaeria in the Niessliaceae(Hypocreales),according to multi-gene phylogenetic analyses(ITS,LSU,rpb2 and tef1).For *** the genus Pseudomassariella is revived.A Leiosphaerellalike fungus on Lycopodium is described as the new species monographella *** addition the phylogenetic relationships of two fungi forming superficial stromata are here clarified:Collodiscula japonica belongs to the Xylariaceae,while melogramma campylosporum may currently be interpreted as representing a family of its own,the melogrammataceae.

关键词： Collodiscula Eucasphaeria.Leiosphaerella massarina melogramma metasphaeria New genus Phylogenetic reconstruction Pseudomassaria Pseudomassariella Systematics

The effect of surface roughness on claw and adhesive hair performance in the dock beetle Gastrophysa viridula

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Insect Science 2011年第3期18卷 298-304页

作者： James m. R. Bullock walter Federle Department of Zoology University of Cambridge Downing Street Cambridge UK

Natural adhesive systems are adapted to attach to rough surfaces, but the underlying mechanisms have not been fully clarified. Attachment forces for the beetle Gastrophysa viridula were recorded on epoxy casts of surfaces with different roughness using a centrifuge device. Replicas were made of standardized polishing paper with asperity sizes ranging from 0.05 to 30 μm and of dock leaves （Rumex obtusifolius）. Beetles adhered with a safety factor of up to 36 times body weight on smooth substrates or on casts of leaves of their host plant. On the rough substrates, forces were much lower and a minimum at small scale roughness （0.05μm asperity size, with a mean safety factor of S） was observed. Removal of the claws led to a significant reduction in force for rough substrates with asperity sizes ≥ 12 μm. Attachment forces of the hairy adhesive system itself（without the claws） slightly increased from small-scale to large-scale surface roughness, but remained below the level seen on the smooth substrate. This is explained by the inability of setal tips to make full contact to the surface.

关键词： adhesion biomechanics claws locomotion roughness tribology

Asterodiscus and Stigmatodiscus,two new apothecial dothideomycete genera and the new order Stigmatodiscales

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Fungal Diversity 2016年第5期80卷 271-284页

作者： Hermann Voglmayr Alain Gardiennet walter m.Jaklitsch Division of Systematic and Evolutionary Botany Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 14A-1030 ViennaAustria 14 rue Roulette F-21260 VéronnesFrance Institute of Forest Entomology Forest Pathology and Forest ProtectionDepartment of Forest and Soil SciencesBOKU-University of Natural Resources and Life SciencesHasenauerstraße 38A-1190 ViennaAustria

During a survey on corticolous Dothideomycetes,several collections with ascospores matching the genera Asteromassaria and Stigmatomassaria(Pleomassariaceae,Pleosporales)were revealed from dead corticated twigs of Acer,Carpinus and *** morphological examination showed that their ascomata were apothecial,with a hamathecium consisting of septate,branched paraphyses,which are apically swollen at *** collections were cultured and sequenced,and a Blast search of their nuc 28S rDNA sequences revealed dothideomycetous affiliation,but without a close match to a specific family or *** analyses of a multigene matrix containing a representative selection of Dothideomycetes from four genes(nuc 18S rDNA,nuc 28S rDNA,rpb2 and tef1)revealed placement within Dothideomycetes but without a supported familial or ordinal *** on the phylogenetic analyses and morphological investigations,the new genera Asterodiscus and Stigmatodiscus,with the two new species *** and ***,are described and illustrated,and placed in the new family Stigmatodiscaceae and new order Stigmatodiscales.

关键词： Ascomycota Dothideomycetes New species Newgenus Newfamily Neworder Phylogenetic analysis Taxonomy

Crystallization kinetics of Sn_(40)Se_(60) thin films for phase change memory applications

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Journal of Semiconductors 2015年第6期36卷 17-20页

作者： Joshua m.Kundu Patrick m.Karimi walter K.Njoroge Department of Physics Kenyatta University

The crystallization kinetics of Sn4oSe6o thin films has been successfully investigated using sheet resis- tance versus temperature measurements. Thermal evaporation was used to deposit the films on ordinary glass sub- strates. The crystallization temperature for Sn4oSe60 thin film was found to be 156.6 -t- 0.3 ~C. In the as-deposited state, the sheet resistance was found to be 195 mf2/[2, this value declined to 1560 f2/[2] upon annealing. The value of activation energy obtained from the Kissinger plot was 0.62 ＋ 0.07 eV. From the results obtained, SnaoSe60 is a promising alloy for PCm application because of its high electrical contrast, high crystallization temperature, and relatively high activation energy.

关键词： crystallization temperature activation energy electrical contrast phase change memory