Search query: sakai ilangovan

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abstract: A ferroelectric memory field effect transistor (FET) with a Pt SrBi/sub 2/Ta/sub 2/O/sub 9/ Hf Al O Si gate stack was fabricated and its electrical properties were characterized. The insulating and ferroelectric layers were successively deposited by a laser ablation technique. Excellent data retention characteristics were obtained. The drain currents of on and off states were measured as a function of time, after /spl plusmn/6 V poling voltage applied to the gate electrode. The current ratio of the on and off states was more than 10/sup 6/ even after 12 days. Moreover, after 10/sup 12/ cycles of /spl plusmn/8 V pulses, this ratio was also more than 10/sup 6/
author_names: Shigeki Sakai

Rajangam Ilangovan
title: Metal ferroelectric insulator semiconductor memory FET with long retention and high endurance
venue: IEEE Electron Device Letters
year: 2004

abstract: A metal ferroelectric insulator semiconductor (MFIS) field effect transistor (FET) composed of a Pt/SrBi2Ta2O9(SBT)/Hf Al O/Si stack with a long data retention over 106 s was fabricated. The poling voltages to obtain the long data retention were 6 V. The memory window in the drain current vs gate voltage (Id Vg) curve increased monotonically with increasing gate scan voltage amplitude (Vscan) up to Vscan=6 V. This behavior indicates that the device operation is based on unsaturated ferroelectric polarization switching. A direct cross sectional transmission electron microscopy image of the Pt/SBT/Hf Al O/Si stack and the electrical properties of a Pt/Hf Al O/Si metal insulator semiconductor (MIS) FET used as a reference showed the existence of a 4.4 nm thick interfacial layer between the Hf Al O layer and the Si substrate, which can explain the device operation with the unsaturated ferroelectric polarization. The results thus concluded that saturation of ferroelectric polarization is not essential for obtaining the long data retention.
author_names: Shigeki Sakai

Rajangam Ilangovan

Mitsue Takahashi
title: Pt/SrBi2Ta2O9/Hf Al O/Si Field Effect Transistor with Long Retention Using Unsaturated Ferroelectric Polarization Switching
year: 2004

abstract: A ferroelectric gate FET (FeFET) is significant for 1T FeRAM. Among fabricated Pt/SrBi/sub 2/Ta/sub 2/O/sub 9/(HfO/sub 2//sub x/(Al/sub 2/O/sub 3//sub 1 x//Si FeFETs, we find that the optimum buffer layer composition ratio, x, of HfO/sub 2/ and Al/sub 2/O/sub 3/ exists around 0.75. A FeFET of x 0.75 with high k buffer layer and low leakage current shows long data retention.
author_names: Shigeki Sakai

M Takahashi

Rajangam Ilangovan
title: Long retention ferroelectric gate FET with a (HfO/sub 2//sub x/(Al/sub 2/O/sub 3//sub 1 x/ buffer insulating layer for 1T FeRAM
venue: IEDM Technical Digest. IEEE International Electron Devices Meeting, 2004.
year: 2004

abstract: Potassium tantalate niobate single crystals have been grown for Nb concentrations 0.7, 0.5 and 0.35. The step cooling technique was adopted to avoid the striations and composition gradient. The composition was analysed using electron probe microanalysis. Dielectric study was carried out for the grown crystals.
author_names: R Ilangovan

Ganesan Ravi

C Subramanian

P Ramasamy

Shigeki Sakai
title: Growth and characterization of potassium tantalate niobate single crystals by the step cooling technique
year: 2002

abstract: Ferroelectric materials and their applications have been known and developed sine 1920s and nowadays they are one of the most important materials used in the memory, optical device and sensor device production. Although they are possible to utilize ferroelectric characteristics for a wide variety of applications, but a primary object of recent research activities is directed toward the development of nonvolatile memories. In this study we focused on enhancement of electrical and data retention characteristics of memory devices based on metal ferroelectric insulator semiconductor (MFIS) structure by radical irradiation treatments. Ferroelectric memories has gathered much attention since they show ultimate properties of nonvolatility, low power consumption, and high speed operation [Hai, L. V. etc. (2010) Hai, L. V. etc. (2006 a) Tarui Y, ect. (1997) Scott, J. F. (2000) Sakai, S. Ilangovan, R. (2004) Ishiwara, H. (2001) The well known ferroelectric memory applications of ferroelectric capacitor type random access memories (FeRAM) have been successfully developed and commercially available at present [Sakai, S. etc. (2010) Another type of ferroelectric memory is a ferroelectric field effect transistor (FeFET) in which a ferroelectric layer was inserted between top gate and oxide layer of an FET, as shown in. In recent years, memory cells of the FeFETs were selected as the most suitable candidate to alternate for floating gate (FG) memory cells in the NAND flash memory, due to the fact that FeFET cells exhibited superior characteristics from viewpoints of downscale ability, long endurance characteristics, and low voltage operation, in comparison with the FG cells [Hai, L. V. etc. (2010) The new Fe NAND flash memory based on the FeFETs can open a new generation of the NAND flash memory which meets fully requirements of high speed USB flash drives, MP3 players, flash memory in portable devices and solid state drive (SSD) applications [Hai, L. V. etc. (2010) Although many efforts have been made by many research groups to improve but the FeFET type memories still need more investigations to satisfy for commercial application as some problems were pointed out. It is extremely difficult to fabrication FeFETs with high quality ferroelectric and insulator films therefore they always do not show acceptable retention and electrical properties. We attribute the relatively low
author_names: Le Van Hai

Takeshi Kanashima

Masanori Okuyama
title: Studies on Electrical Properties and Memory Retention Enhancement of Metal Ferroelectric Insulator Semiconductor with Radical Irradiation Treatments
year: 2018

abstract: Verocytotoxigenic Escherichia coli (VTEC) can contaminate crop plants, potentially using them as secondary hosts, which can lead to food borne infection. Currently, little is known about the influence of the specific plant species on the success of bacterial colonization. As such, we compared the ability of the VTEC strain, E. coli O157:H7 'Sakai, to colonize the roots and leaves of four leafy vegetables: spinach (Spinacia oleracea) lettuce (Lactuca sativa) vining green pea (Pisum sativum) and prickly lettuce (Lactuca serriola) a wild relative of domesticated lettuce. Also, to determine the drivers of the initial response on interaction with plant tissue, the whole transcriptome of E. coli O157:H7 Sakai was analyzed following exposure to plant extracts of varying complexity (spinach leaf lysates or root exudates, and leaf cell wall polysaccharides from spinach or lettuce) Plant extracts were used to reduce heterogeneity inherent in plant microbe interactions and remove the effect of plant immunity. This dual approach provided information on the initial adaptive response of E. coli O157:H7 Sakai to the plant environment together with the influence of the living plant during bacterial establishment and colonization. Results showed that both the plant tissue type and the plant species strongly influence the short term (1 h) transcriptional response to extracts as well as longer term (10 days) plant colonization or persistence. We show that propagation temperature (37 vs. 18degC) has a major impact on the expression profile and therefore pre adaptation of bacteria to a plant relevant temperature is necessary to avoid misleading temperature dependent wholescale gene expression changes in response to plant material. For each of the plant extracts tested, the largest group of (annotated) differentially regulated genes were associated with metabolism. However, large scale differences in the metabolic and biosynthetic pathways between treatment types indicate specificity in substrate utilization. Induction of stress response genes reflected the apparent physiological status of the bacterial genes in each extract, as a result of glutamate dependent acid resistance, nutrient stress, or translational stalling. A large proportion of differentially regulated genes are uncharacterized (annotated as hypothetical) which could indicate yet to be described functional roles associated with plant interaction for E. coli O157:H7 Sakai.
author_names: Louise Crozier

Peter E Hedley

Jenny Morris

Carol Wagstaff

Simon C Andrews

Ian K Toth

Robert W Jackson

Nicola Jean Holden
title: Whole Transcriptome Analysis of Verocytotoxigenic Escherichia coli O157:H7 (Sakai) Suggests Plant Species Specific Metabolic Responses on Exposure to Spinach and Lettuce Extracts
venue: Front. Microbiol.
year: 2016

abstract: We revisit and extend previous calculations of glueball decay rates in the Sakai Sugimoto model, a holographic top down approach for QCD with chiral quarks based on D8 probe branes in Witten's holographic model of nonsupersymmetric Yang Mills theory. The rates for decays into two pions, two vector mesons, four pions, and the strongly suppressed decay into four pi0 are worked out quantitatively, using a range of the 't Hooft coupling which closely reproduces the decay rate of rho and omega mesons and also leads to a gluon condensate consistent with QCD sum rule calculations. The lowest holographic glueball, which arises from a rather exotic polarization of gravitons in the supergravity background, turns out to have a significantly lower mass and larger width than the two widely discussed glueball candidates f0(1500) and f0(1710) The lowest nonexotic and predominantly dilatonic scalar mode, which has a mass of 1487 MeV in the Witten Sakai Sugimoto model, instead provides a narrow glueball state, and we conjecture that only this nonexotic mode should be identified with a scalar glueball component of f0(1500) or f0(1710) Moreover the decay pattern of the tensor glueball is determined, which is found to have a comparatively broad total width when its mass is adjusted to around or above 2 GeV.
author_names: Frederic Brunner

Denis Parganlija

Anton K Rebhan
title: Glueball Decay Rates in the Witten Sakai Sugimoto Model
year: 2015

abstract: We estimate the consequences of finite masses of pseudoscalar mesons on the decay rates of scalar glueballs in the Witten Sakai Sugimoto model, a top down holographic model of low energy QCD, by extrapolating from the calculable vertex of glueball fields and the e^ meson that follows from the Witten Veneziano mechanism for giving mass to the latter. Evaluating the effect on the recently calculated decay rates of glueballs in the Witten Sakai Sugimoto model, we find a strong enhancement of the decay of scalar glueballs into kaons and e mesons, in fairly close agreement with experimental data on the glueball candidate f_{0}(1710)
author_names: Frederic Brunner

Anton K Rebhan
title: Nonchiral Enhancement of Scalar Glueball Decay in the Witten Sakai Sugimoto Model.
venue: Physical review letters
year: 2015

abstract: A brief review of the Witten Sakai Sugimoto model is given, which is a top down holographic model of low energy QCD with chiral quarks derived from type IIA superstring theory. The main predictions of the model, in particular concerning meson spectra, the gluon condensate, the QCD string tension, the mass of the \eta' and of baryons are discussed and compared quantitatively with available experimental and/or lattice results. Then some recent results of potential interest to the physics program at the future FAIR facility are presented: The spectrum of glueballs and their decay rates into pions, and the phase diagram of QCD at finite temperature, density, and magnetic field strength.
author_names: Anton K Rebhan
title: The Witten Sakai Sugimoto model: A brief review and some recent results
year: 2014

abstract: A bstractThe Sakai Sugimoto model is the preeminent example of a string theory description of holographic QCD, in which baryons correspond to topological solitons in the bulk. Here we investigate the validity of various approximations of the Sakai Sugimoto soliton that are used widely to study the properties of holographic baryons. These approximations include the flat space self dual instanton, a linear expansion in terms of eigenfunctions in the holographic direction and an asymptotic power series at large radius. These different approaches have produced contradictory results in the literature regarding properties of the baryon, such as relations for the electromagnetic form factors. Here we determine the regions of validity of these various approximations and show how to relate different approximations in contiguous regions of applicability. This analysis clarifies the source of the contradictory results in the literature and resolves some outstanding issues, including the use of the flat space self dual instanton, the detailed properties of the asymptotic soliton tail, and the role of the UV cutoff introduced in previous investigations. A consequence of our analysis is the discovery of a new large scale, that grows logarithmically with the 't Hooft coupling, at which the soliton fields enter a nonlinear regime. Finally, we provide the first numerical computation of the Sakai Sugimoto soliton and demonstrate that the numerical results support our analysis.
author_names: Stefano Bolognesi

Paul Sutcliffe
title: The Sakai Sugimoto soliton
year: 2014