Role of Single Defects in Electronic Transport through Carbon Nanotube Field-Effect Transistors

The influence of defects on electron transport in single-wall carbon nanotube field effect transistors (CNFETs) is probed by combined scanning gate microscopy (SGM) and scanning impedance microscopy (SIM). SGM reveals a localized field effect at discrete defects along the CNFET length. The depletion surface potential of individual defects is quantified from the SGM-imaged radius of the defect as a function of tip bias voltage. This provides a measure of the Fermi level at the defect with zero tip voltage, which is as small as 20 meV for the strongest defects. The effect of defects on transport is probed by SIM as a function of backgate and tip-gate voltage. When the backgate voltage is set so the CNFET is "on" (conducting), SIM reveals a uniform potential drop along its length, consistent with diffusive transport. In contrast, when the CNFET is "off", potential steps develop at the position of depleted defects. Finally, high-resolution imaging of a second set of weak defects is achieved in a new "tip-gated" SIM mode.Comment: to appear in Physical Review Letter

Tip-gating Effect in Scanning Impedance Microscopy of Nanoelectronic Devices

Electronic transport in semiconducting single-wall carbon nanotubes is studied by combined scanning gate microscopy and scanning impedance microscopy (SIM). Depending on the probe potential, SIM can be performed in both invasive and non-invasive mode. High-resolution imaging of the defects is achieved when the probe acts as a local gate and simultaneously an electrostatic probe of local potential. A class of weak defects becomes observable even if they are located in the vicinity of strong defects. The imaging mechanism of tip-gating scanning impedance microscopy is discussed.Comment: 11 pages, 3 figures, to be published in Appl. Phys. Let

Carbon nanotubes as a tip calibration standard for electrostatic scanning probe microscopies

Scanning Surface Potential Microscopy (SSPM) is one of the most widely used techniques for the characterization of electrical properties at small dimensions. Applicability of SSPM and related electrostatic scanning probe microscopies for imaging of potential distributions in active micro- and nanoelectronic devices requires quantitative knowledge of tip surface contrast transfer. Here we demonstrate the utility of carbon-nanotube-based circuits to characterize geometric properties of the tip in the electrostatic scanning probe microscopies (SPM). Based on experimental observations, an analytical form for the differential tip-surface capacitance is obtained.Comment: 14 pages, 4 figure

Harvesting Entities from the Web Using Unique Identifiers -- IBEX

In this paper we study the prevalence of unique entity identifiers on the Web. These are, e.g., ISBNs (for books), GTINs (for commercial products), DOIs (for documents), email addresses, and others. We show how these identifiers can be harvested systematically from Web pages, and how they can be associated with human-readable names for the entities at large scale. Starting with a simple extraction of identifiers and names from Web pages, we show how we can use the properties of unique identifiers to filter out noise and clean up the extraction result on the entire corpus. The end result is a database of millions of uniquely identified entities of different types, with an accuracy of 73--96% and a very high coverage compared to existing knowledge bases. We use this database to compute novel statistics on the presence of products, people, and other entities on the Web.Comment: 30 pages, 5 figures, 9 tables. Complete technical report for A. Talaika, J. A. Biega, A. Amarilli, and F. M. Suchanek. IBEX: Harvesting Entities from the Web Using Unique Identifiers. WebDB workshop, 201

Three new species of Grouvellinus Champion, 1923 from Maliau Basin, Sabah, Borneo, discovered by citizen scientists during the first Taxon Expedition (Insecta, Coleoptera, Elmidae)

Further results are presented of the first field course at Maliau Basin, Malaysian Borneo organized by Taxon Expeditions, an organization which enables citizen scientists to be directly involved in taxonomic discoveries. Three new species of the aquatic beetle genus Grouvellinus Champion, 1923, namely G. leonardodicaprioi sp. n., G. andrekuipersi sp. n., and G. quest sp. n. were collected jointly by the citizen scientists and taxonomists during the fieldwork in Maliau Basin. Material was mainly sampled from sandstone bottom rocks of blackwater streams at altitudes between 900 m and 1,000 m using fine-meshed hand-nets. The genus is widely distributed in the Oriental and Palearctic regions, but these are the first records from the island of Borneo

A new intertidal shore bug (Heteroptera: Saldidae) from the Philippines

Salduncula carmencitae sp.n. is described, its habitus and the paramere and parandria of the male are illustrated. This shore bug was found on Mindanao Island, the Philippines, in the intertidal zone. Habitat and behaviour of the species are briefly described. The distinguishing diagnostic characters of species of Salduncula Brown, 1954 are discussed

Laser‐induced desorption of NO from NiO(100): Ab initio calculations of potential surfaces for intermediate excited states

In order to interpret the experimental results of the state resolved UV‐laser‐induced desorption of NO from NiO(100) (rotational and vibrational populations, velocity distributions of the desorbing NO molecules, etc.), we have performed ab initio complete active space self‐consistent field (CASSCF) and configuration interaction (CI) calculations for the interaction potential between NO and the NiO(100) surface in the electronic ground state and for those excited states which are involved in the desorption process. The NiO(100)–NO distance and the tilt angle between the NO axis and the surface normal have been varied. A cluster model containing a NiO8−5‐cluster embedded in a Madelung potential has been used for representing the NiO(100) surface. The excited states which are important for the desorption process, are charge transfer states of the substrate–adsorbate system, in which one electron is transferred from the surface into the NO‐2π‐orbital. The potential curves of these excited charge transfer states show deep minima (4 eV–5 eV) at surface/NO distances which are smaller than that in the ground state. The angular dependence of these potentials behaves similar as in the ground state. A semiempirical correction to the calculated excitation energies has been added which makes use of the bulk polarization of NiO. With this correction the charge transfer states are considerably stabilized. The lowest excitation energy amounts to about 4 eV which is in reasonable agreement with the onset of the laser desorption observed experimentally at about 3.5 eV. The density of the NO−‐like states is rather high, so that probably several excited states are involved in the desorption process. The potential energy curves for all of these states are quite similar, but the transitions from the ground state into different excited charge transfer states show strongly differing oscillator strengths, which are also strongly dependent on the surface/NO distance. This fact is important for the dynamics of the deexcitation process in the sense of a selection criterion for the states involved. The magnitude of the oscillator strengths is large in comparison with the excitation of NO in the gas phase, which might be an indication for the possibility of optical excitation processes. One dimensional wave packet calculations on two potential energy curves using fixed lifetimes for the excited state in each calculation have been performed and enable us to estimate the mean lifetime of the excited state to be 15 fs≤τ≤25 fs. This implies that the dynamics of the system is dominated by the attractive part of the excited state potential

Carbon Nanotubes as Schottky Barrier Transistors

We show that carbon nanotube transistors operate as unconventional "Schottky barrier transistors", in which transistor action occurs primarily by varying the contact resistance rather than the channel conductance. Transistor characteristics are calculated for both idealized and realistic geometries, and scaling behavior is demonstrated. Our results explain a variety of experimental observations, including the quite different effects of doping and adsorbed gases. The electrode geometry is shown to be crucial for good device performance.Comment: 4 pages, 5 figures, appears in Physical Review Letter

Humble Adorations Behind Kakawin Banawa Sekar Tanakung: a Critical Discourse Analysis

This research which deals with critical discourse analysis aims (1) to find out meanings of terms and vocabularies in Kakawin Banawa Sekar Tanakung, (2) to analyze meanings of Kakawin Banawa Sekar Tanakung in religious context, and (3) to reveal ideology behind the Kakawin Banawa Sekar Tanakung. The subject of this study was Kakawin Banawa Sekar Tanakung in ancient Javanese language, while the techniques of data collections were documentation. The data was then analyzed descriptively based on theory of Critical Discourse Analysis, theory of Natural Semantic Metalanguage and theory of meaning. The results of data analysis show that (1) most meanings of terms and vocabularies in the Kakawin Banawa Sekar Tanakung were reduced and broadened due to the influence of local culture and historical events. Some words are still common in today\u27s society, especially the Balinese in which ancient Javanese literatures are kept preserved today. (2) Kakawin Banawa Sekar Tanakung has a religious and ethical meaning, that people\u27s life in the ancient Java was religiously patterned. Besides, the kakawin showed that people of the ancient Java maintained their respects and submissiveness to the royal authorities. (3) The ideology of Kakawin Banawa Sekar Tanakung is submissive adoration, seen from the way the poet selected words and presented the kakawin through humble language choices. Considering that kakawins have valuable religious, moral, and educational values, further research on ancient Javanese literature are needed. Critical analysis according to the context of the kakawin should be conducted for the raise of Indonesian research on local assets. 2 PUJIAN DENGAN KERENDAHAN HATI DALAM KAKAWIN BANAWA SEKAR TANAKUNG: SEBUAH ANALISIS WACANA KRITIS oleh Ida Bagus Arya Lawa Manuaba NIM. 1029011062 Jurusan Pendidikan Bahasa Program Pascasarjana Universitas Pendidikan Ganesha Juli 201

On Convergence of the Inexact Rayleigh Quotient Iteration with the Lanczos Method Used for Solving Linear Systems

For the Hermitian inexact Rayleigh quotient iteration (RQI), the author has established new local general convergence results, independent of iterative solvers for inner linear systems. The theory shows that the method locally converges quadratically under a new condition, called the uniform positiveness condition. In this paper we first consider the local convergence of the inexact RQI with the unpreconditioned Lanczos method for the linear systems. Some attractive properties are derived for the residuals, whose norms are $\xi_{k+1}$'s, of the linear systems obtained by the Lanczos method. Based on them and the new general convergence results, we make a refined analysis and establish new local convergence results. It is proved that the inexact RQI with Lanczos converges quadratically provided that $\xi_{k+1}\leq\xi$ with a constant $\xi\geq 1$. The method is guaranteed to converge linearly provided that $\xi_{k+1}$ is bounded by a small multiple of the reciprocal of the residual norm $\|r_k\|$ of the current approximate eigenpair. The results are fundamentally different from the existing convergence results that always require $\xi_{k+1}<1$, and they have a strong impact on effective implementations of the method. We extend the new theory to the inexact RQI with a tuned preconditioned Lanczos for the linear systems. Based on the new theory, we can design practical criteria to control $\xi_{k+1}$ to achieve quadratic convergence and implement the method more effectively than ever before. Numerical experiments confirm our theory.Comment: 20 pages, 8 figures. arXiv admin note: text overlap with arXiv:0906.223