Window Shift Research Articles

Effects of blocking oxide layer types on the performance of nonvolatile floating gate memory containing AgInSbTe-SiO2 nanocomposite thin films

Influence of blocking oxide layer types on the performance of nonvolatile floating gate memory (NFGM) containing AgInSbTe (AIST)-SiO2 nanocomposite as the charge-trapping layer was investigated. In the NFGM containing a 7-nm thick SiO2 blocking oxide layer deposited by plasma-enhanced chemical vapor deposition (PECVD), a fairly large memory window (ΔVFB) shift of 20.9V with the charge density of 1.3×1013cm−2 at ±15V gate voltage sweep was achieved. As to the NFGM containing HfO2 blocking oxide layer, the device performance was inferior to that of PECVD-SiO2 device due to the diffusion of HfO2 into the nanocomposite layer. Interdiffusion resulted in the formation of HfSiOx phase and oxygen defects which might act as the leakage paths, consequently deteriorating the charge trapping efficiency of AIST nanocrystals (NCs) embedded in nanocomposite layer. Analytical results illustrated that the film quality and barrier height feature of blocking oxide layer are essential to form the deep trap sites in the programming layer to achieve a satisfactory NFGM performance with long-term reliability.

On-Chip Multiple Electromagnetically Induced Transparencies in Photon–Plasmon Composite Nanocavities

Chip-integrated multiple electromagnetically induced transparencies are realized using a photon–plasmon composite nanocavity (composed of a single photonic crystal nanocavity coupled with a single plasmonic nanocavity), i.e., comprehensively utilizing the superiorities of photonics as well as plasmonics. The destructively interferential coupling of one broad-band plasmonic nanocavity mode with two narrow-band silicon photonic crystal nanocavity modes generates two electromagnetically induced transparency windows. The two transparency windows simultaneously have a narrow line width of 15 nm, a high transmission contrast of 70%, and a strong slow light effect. A large group refractive index of more than 400 is obtained at the transparency window center, indicating a 10-fold increase in comparison with earlier results. The photon–plasmon composite nanocavity has a feature size of only 2 μm. The transparency window shifts 30 nm for the photon–plasmon composite nanocavity covered with a monolayer of graphene e...

Time Window as a Self-Control Denominator: Shorter Windows Shift Preference toward Virtues and Longer Windows toward Vices

When planning future consumption, individuals are known to opt for large virtue quantities and small vice quantities as a means of self-control. We argue that such planning may also involve the time window within which a given quantity needs to be consumed because the final objective is to plan for a desired consumption rate (i.e., quantity/time window)—a high virtue rate and a low vice rate. Five studies reveal that, holding quantity constant, a short window (i.e., high rate) nudges individuals toward virtues, and a long window (i.e., low rate) toward vices. We find this effect for hypothetical and real virtue-vice choices, preferences, and willingness to extend a time window. Furthermore, these effects are mediated by the pursuit of long-term health goals; and are moderated such that the effect of time windows is stronger for those who need more help in meeting their self-control goals: impulsive individuals. While these effects are consistent with self-control, we discuss a blend of mechanisms that may be working in conjunction, particularly at the stage that we focus on: planning rather than consuming. Our results offer strong theoretical implications and important consequences for the marketplace where expiration periods and other time windows are ubiquitous.

General Theory for Pulse Voltammetric Techniques at Rough Electrodes: Multistep Reversible Charge Transfer Mechanism

Theoretical model is developed for the voltammetric response of multistep reversible charge transfer mechanism at rough electrode. This theory is applicable for arbitrary as well as random roughness profiles. An explicit mathematical expression relating the staircase (SCV), cyclic staircase (CSCV), differential pulse (DPV) and square wave (SWV) voltammetric response of finite fractal electrode to the statistical morphological characteristics is obtained. The fractal characteristics, viz. fractal dimension (DH), lower length scale of fractality (ℓ) and topothesy length (ℓτ) are found to dominantly control the various voltammetric techniques responses of a multistep charge transfer mechanism. The heights of the voltammetric peaks corresponding to each charge transfer step is found to increase with increasing roughness. In CSCV, the anomalous intermediate scan rate window of Randles-Sevc˘ik plots shifts with the number of charge transfer step. The peak current for the charge transfer step occurring at lower potential has an early onset of the influence of morphology, i.e., the anomalous regime window shifts at lower scan rates compared to those occurring at higher potential values. The differential techniques show roughness induced current enhancement for all the peaks without affecting the position of the peak potential. Thus, roughness helps to overcome the major drawback of low Faradaic current in these techniques and improves their application for chemical sensing purposes.

Tunable Transmission-Line Metamaterials Mimicking Electromagnetically Induced Transparency

Tunable transmission-line (TL) metamaterials mimicking electromagnetically induced transparency (EIT) have been studied. Firstly, two types of tunable TL EIT-like metamaterial, based on the double split-ring resonator (DSRR) and single split-ring resonator (SSRR), were fabricated and their transmission properties carefully compared. The results showed that the transmittance maximum was almost invariable with shift of the transparency window for the tunable DSRR-based TL EIT-like metamaterial, but for the tunable SSRR-based TL EIT-like metamaterial, the transmittance maximum gradually diminished with shift of the transparency window toward the center of the absorption band. Moreover, the reason for these different transmission properties was explored, revealing that the reduction of the transmittance maximum of the transparency window for the tunable SSRR-based TL EIT-like metamaterial is mainly due to energy loss caused by the resistance of the loaded varactor diodes.

Haar wavelet spectrum of sin2-pulsed driven qubit

The transient scattered spectrum with Haar wavelet window function is calculated analytically for a resonant pulsed driven qubit (taken as spin-12 2-level atom). The pulse shape is taken as the sequential laser sin2-pulse. Effect of the window function dilation and shift parameters are associated with the pulse strength and the initial atomic state. In particular, for strong pulse strength and increasing shift parameter: (i) the 3-peak structure turns into a central broader peak with ‘hole burning’ at its centre, only, for the case of initial ground state, and not with the initial excited state, (ii) for the case of initial atomic coherent state, the 3-peak structure has an oscillatory envelope due to the non-zero initial coherent dipole field.

Damage detection of multi-story shear buildings due to earthquakes by model updating method

In this paper, we present a novel model updating method for damage detection of multi-story shear buildings during severe earthquakes. The story stiffnesses are explicitly presented in an incremental manner; this enables a simple and robust algorithm for the purpose of identification of the story stiffnesses. The estimated modal data, including natural frequencies and mode shapes of lower modes, are used in the proposed algorithm; moreover, sensitivity analysis of natural circular frequencies is incorporated to reduce possible errors. The story stiffnesses are identified by an iterative algorithm, and the window shift technique is adopted to present change of the story stiffness due to damages in the buildings during earthquakes. Numerical examples demonstrate that the proposed method is of high accuracy, even when the recorded responses are polluted by a relatively high level of (white) noises. Copyright © 2016 John Wiley & Sons, Ltd.

Axion phenomenology and θ-dependence from N f = 2 + 1 lattice QCD

We investigate the topological properties of $N_f = 2+1$ QCD with physical quark masses, both at zero and finite temperature. We adopt stout improved staggered fermions and explore a range of lattice spacings $a \sim 0.05 - 0.12$ fm. At zero temperature we estimate both finite size and finite cut-off effects, comparing our continuum extrapolated results for the topological susceptibility $\chi$ with predictions from chiral perturbation theory. At finite temperature, we explore a region going from $T_c$ up to around $4\, T_c$, where we provide continuum extrapolated results for the topological susceptibility and for the fourth moment of the topological charge distribution. While the latter converges to the dilute instanton gas prediction the former differs strongly both in the size and in the temperature dependence. This results in a shift of the axion dark matter window of almost one order of magnitude with respect to the instanton computation.

Widely tunable alloy composition and crystal structure in catalyst-free InGaAs nanowire arrays grown by selective area molecular beam epitaxy

We delineate the optimized growth parameter space for high-uniformity catalyst-free InGaAs nanowire (NW) arrays on Si over nearly the entire alloy compositional range using selective area molecular beam epitaxy. Under the required high group-V fluxes and V/III ratios, the respective growth windows shift to higher growth temperatures as the Ga-content x(Ga) is tuned from In-rich to Ga-rich InGaAs NWs. Using correlated x-ray diffraction, transmission electron microscopy, and micro-photoluminescence spectroscopy, we identify structural defects to govern luminescence linewidths in In-rich (x(Ga) < 0.4) and Ga-rich (x(Ga) > 0.6) NWs, whereas limitations at intermediate Ga-content (0.4 < x(Ga) < 0.6) are mainly due to compositional inhomogeneities. Most remarkably, the catalyst-free InGaAs NWs exhibit a characteristic transition in crystal structure from wurtzite to zincblende (ZB) dominated phase near x(Ga) ∼ 0.4 that is further reflected in a cross-over from blue-shifted to red-shifted photoluminescence emission relative to the band edge emission of the bulk ZB InGaAs phase.

Versatile pyridine-2,6-bis-tetrazolate scaffolds for the formation of highly luminescent lanthanide complexes.

Here we report the straightforward synthesis of the ligands L(tz), L(tzC8), L(tzPEG), L(tzAnis) and L(≡Anis) presenting the same pyridine-bistetrazolate (pytz, L) chelating scaffold but different substituents on the para position of the pyridine ring. Its substitution allows the tuning of the solubility of the LnIII complexes [Ln(Li)3]3(-). These new ligands form homoleptic nona-coordinated LnIII complexes of analogous structure and comparable stability in water and methanol. The derivatization of the para position with triazole and substituted triazole groups does not lead to a significant shift of the absorption window, but a shift of 40 nm is observed in ligand L(≡Anis) due to the presence of the p-ethynyl anisole fragment. The L(tzX) series sensitize well, both the Eu and the Tb ions with quantum yields up to 98% for Tb and 43% for Eu, while the ligand L(≡Anis) sensitizes well Eu (QY of 48%) but cannot sensitize Tb due to the position of its triplet state.

Microscopic analysis of gain spectrum of surface plasmons in graphene

In this paper, microscopic interactions of surface plasmons and carriers in the graphene layer are investigated and based on the second quantization formalism, rate equations of surface plasmons are presented. Plasmonic matrix element for surface plasmon-induced transitions in the graphene is also analytically studied. We have shown TE plasmonic modes, due to vanishing plasmonic matrix elements, cannot be amplified in the graphene layer and amplification is only possible for TM plasmonic modes. Using the rate equation and the plasmonic matrix element, we have investigated emission and absorption spectra of surface plasmons in graphene for thermal equilibrium, optical induced population inversion and carrier-injected inversion regimes in the graphene layer and demonstrated that only interband band processes are involved in the surface plasmon emission. We have shown optical pumping opens a gain window for large wavenumbers and the gain window shifts toward larger wavenumbers by increasing pump energy, while carrier injection provides gain for small wave numbers.

Experimental and Modeling Study of Domain Orientation in Confined Block Copolymer Thin Films

Use of block copolymer thin films in lithographic applications requires orientation of domains perpendicular to a substrate. Algebraic models were used to predict conditions that are favorable for perpendicular versus parallel domain orientation in films confined between two interfaces. The free energy of each orientation was evaluated, yielding response surface plots as a function of film thickness and the preferential interaction strength at each interface. The model predicts that perpendicular orientation is generally favored for thinner films and at thicknesses incommensurate with the bulk periodicity, L0. If either the top or bottom interfaces are preferential for one block, the favorable thickness windows shift depending on the interface wetting behavior. An extensive body of thin film experimental work corroborated the analytical predictions. The algebraic model has predictive value, and it demonstrates the complexity of the dependence of block copolymer orientation on the wetting behavior of the i...

Promotional effect of microwave hydrothermal treatment on the low-temperature NH3-SCR activity over iron-based catalyst

Microwave hydrothermal was introduced into the preparation of iron–cerium–titanium mixed oxide catalyst for NH3-SCR of NOx, and the catalysts after microwave hydrothermal treatment or not are characterized by X-ray diffraction (XRD), Infrared spectrum (IR), Transmission Electron Microscope (TEM), nitrogen adsorption–desorption and temperature programmed desorption (NH3/NO-TPD). Microwave hydrothermal treatment enhanced the low-temperature NH3-SCR activity of iron–cerium–titanium mixed oxide catalyst, and made its NH3-SCR reactive temperature window shift to the low-temperature region. Microwave hydrothermal treatment accelerated the crystallite rate of the precursors for iron–cerium–titanium mixed oxide catalysts, adjusted the microscopic pore structure of catalyst, and enlarged the pore diameter and the pore volume of catalyst. Microwave hydrothermal treatment increases Fe and Ce dispersion on the surface of catalyst, and the molar ratio of Ce3+/Ce4+ on the surface of mixed oxide catalyst could also be enhanced after microwave hydrothermal treatment, and improved the relative concentration of Ce3+, thereby enhanced the oxidation and reduction properties of catalyst. At the same time, microwave hydrothermal treatment enhanced the low-temperature adsorption intensity of NH3 over catalyst, thereby enhanced the low-temperature SCR activity of iron–cerium–titanium mixed oxide catalyst.

The influence of reaction times on structural, optical and luminescence properties of cadmium telluride nanoparticles prepared by wet-chemical process

This paper explains one pot synthesis of type II water soluble L-cysteine capped cadmium telluride (CdTe) core shell quantum dots using cadmium acetate, potassium tellurite and L-cysteine as the starting materials. The reaction was carried out in a single three necked flask without nitrogen under reflux at 100°C. Results from PL show a sharp absorption excitonic band edge of the CdTe core with respect to the core shell which loses its shoulder during the growth of the shell on the core. The PL spectra indicate a drastic shift in emission window of the core which is simultaneously accompanied by an increase in emission intensity. X-ray diffraction pattern confirms the formation of hexagonal phase for all samples. Some difference in absorption edges were observed due to varying synthesis time of CdTe NPs. The position of the absorption band is observed to shift towards the lower wavelength side for shorter durations of synthesis.

Electrical and optical properties of compositionally spread MoInSnO thin films deposited by combinatorial RF magnetron cosputtering

Using a combinatorial cosputtering method, we have deposited MoInSnO transparent conducting oxide (TCO) films at various gas ratios, constituent compositions, and film thicknesses to control the transparency window in the infrared and ultraviolet wavelength regions. The MoInSnO thin films showed a minimum sheet resistance of 8.25 Ω/□ and a transmittance of 90% (at 550 nm) when deposited at a substrate temperature of 350 °C, a film thickness of 298 nm, and an elemental composition ratio of 2.8/84.2/13.0 at. % (Mo/In/Sn, at. %). The carrier concentration of a MoInSnO film deposited in an Ar gas atmosphere was higher than that of an InSnO (ITO) film. The MoInSnO film also showed a shift of the transparency window to the short-wavelength region in the infrared range compared with the ITO film. However, the film resistivity increased and the transparency window shifted to the long-wavelength region with increasing O2 gas ratio. The absorption edge of the MoInSnO film in the ultraviolet region shifted to the short-wavelength region with increasing Mo content in the film.

Modulation of charge trapping and current-conduction mechanism of TiO2-doped HfO2 gate dielectrics based MOS capacitors by annealing temperature

Current conduction mechanisms of Hf1−xTixO2-gated metal–oxide–semiconductor (MOS) capacitors depending on various post-annealing temperature (PDA) have been investigated. The sample subjected to 400 °C annealing exhibits superior performance with negligible hysteresis memory window shift (ΔVfb = 0.005 V) and lowest gate leakage current density (5.4 × 10−5 A/cm−2 at Vg = 2 V). In addition, evolution of density of interface traps (Dit), border charger density (Not) and oxide charge density (Qox) as a function of annealing temperature were investigated in details. Detailed electrical measurements reveal that the dominant current conduction behaviors are Poole–Frankel (P–F) emission in the region of low electric fields and Schottky Emission (SE) in the region of high electric fields for gate injection. For substrate injection, however, is mainly via Ohm's conduction, Schottky emission (SE) conduction mechanism serves in low applied field in the samples, respectively.

Thermal Behavior of NMC Cathodes While Ageing

Electric mobility is a growing sector and already nowadays one of the driving forces in the development of cheap, powerful, long lasting and safe lithium-ion batteries. Due to the variability of the lithium-ion technology not only one combination of cathodes and anodes is possible and used. A very promising combination for electric vehicles seems to be a graphitic anode together with lithium nickel manganese cobalt oxide cathodes (Li1(NixMnyCo1-x-y)O2 or NMC). The first composition on the market was the 1:1:1 NMC where the three transition metals have the same share [1]. These materials are known for a high energy and power density, also the lifetime performance shows feasible results for the electric vehicle application [2]. In this work a commercial lithium-ion cell was used to study the thermal behavior of the positive electrode from un-aged and aged cells in order to access the safety of the battery. The selected battery is a Sanyo UR18650E round cell with a capacity of 2050 mAh and consists of a graphitic anode and a NMC cathode (1:1:1). The exact composition of the cathode was gained by an ICP-OES measurement and confirmed the 1:1:1 composition (Ni 32%; Mn 32%; Co 36%). Details of the ageing process and resulting ageing behavior can be found in an earlier publication [2]. The thermal behavior of the positive electrodes is studied with a TGA-DSC and the full cell was studied with an accelerated rate calorimeter (ARC). Due to the delamination of the anode after ageing this electrode could not be used for further investigations. When a lithium-ion battery ages the anode consumes lithium and electrolyte by additional forming of solid electrolyte interface (SEI) [3]. The consumed lithium is delivered by the cathode which changes the cells balancing over time and leads to an overcharge of the cathode due to a shift of the voltage window. This was shown by Krüger et al. [4] with reference electrode measurements at NMC vs. graphite batteries. To study the thermal behavior and measure the onset temperature for the thermal runaway of the cathodes TGA-DSC measurements have been performed. The sample preparation started with the opening of selected cells under argon atmosphere. Cathode samples with a 16 mm diameter were harvested to build coin cells. These cells were used to adjust of SoC in the cathode material. The coin cells were afterwards opened again in a glove box and samples with a diameter of 4mm were taken for the thermal characterization. This is done by heating up the samples with a Mettler-Toledo TGA-DSC under nitrogen atmosphere with a heating rate of 10 K/min from room temperature (25 °C) to 400 °C. The results of the cathode from a new cell at four voltages can be seen in figure 1. The thermal behavior of the un-aged and the aged cell at 4.8 V is compared in figure 2. The aged cell was cycled symmetrically with 1C at 35°C between 100 % and 90 % SoC and had a remaining capacity of 52.6 %. The sample from the un-aged cell shows a less exothermic behavior and also the temperature of the thermal runaway is significantly lower. To study the influence on the full cell, also the thermal behavior of aged and new cells were tested. The results indicate that the ageing has a strong influence on the onset temperature for an exothermic reaction at the cathode and with this also a strong influence on the safety of lithium-ion batteries. This should be considered especially when cells are selected for second life applications.

Room-temperature zero thermal expansion in a cubic perovskite oxide SrCu3Fe4−xMnxO12

A zero thermal expansion in a wide temperature range including room temperature has been achieved in a cubic perovskite oxide SrCu3Fe4−xMnxO12 for x = 1.5. Partial substitution of Mn for Fe in SrCu3Fe4O12 systematically changes the linear thermal expansion coefficient from negative [−6.4(2), −5.7(5), and −1.88(11) ppm/K for x = 0.5, 1, and 1.25, respectively] to almost zero [0.67(15) ppm/K for x = 1.5] to positive [2.97(17) ppm/K for x = 1.75] and the operational temperature window shifts to higher temperature ranges above room temperature. Crystal structure analysis and Mössbauer spectroscopy reveal that the zero thermal expansion for x = 1.5 composition is induced by intermetallic charge transfer between Cu and (Fe,Mn) ions. These results display the high potential of SrCu3Fe4−xMnxO12 for the development of zero thermal expansion materials.

On surface order and disorder of α-pinene-derived secondary organic material.

The surfaces of secondary organic aerosol particles are notoriously difficult to access experimentally, even though they are the key location where exchange between the aerosol particle phase and its gas phase occurs. Here, we overcome this difficulty by applying standard and sub- 1 cm(-1) resolution vibrational sum frequency generation (SFG) spectroscopy to detect C-H oscillators at the surfaces of secondary organic material (SOM) prepared from the ozonolysis of α-pinene at Harvard University and at the University of California, Irvine, that were subsequently collected on Teflon filters as well as CaF2 windows using electrostatic deposition. We find both samples yield comparable SFG spectra featuring an intense peak at 2940 cm(-1) that are independent of spectral resolution and location or method of preparation. We hypothesize that the SFG spectra are due to surface-active C-H oscillators associated with the four-membered ring motif of α-pinene, which produces an unresolvable spectral continuum of approximately 50 cm(-1) width reminiscent of the similar, albeit much broader, O-H stretching continuum observed in the SFG spectra of aqueous surfaces. Upon subjecting the SOM samples to cycles in relative humidity (RH) between <2% RH and ∼95% RH, we observe reversible changes in the SFG signal intensity across the entire spectral range surveyed for a polarization combination probing components of the vibrational transition dipole moments that are oriented parallel to the plane of incidence, but no signal intensity changes for any other polarization combination investigated. These results support the notion that the C-H oscillators at the surfaces of α-pinene-derived SOM deposited on CaF2 windows shift back and forth between two different molecular orientation distributions as the RH is lowered (more ordered) or raised (less ordered). The findings thus point toward the presence of a reversible surface switch for hindering (more ordered, <2%RH) and promoting (less ordered, ∼95%RH) exchange between the aerosol particle phase and its gas phase.

Carrier transport mechanisms of multilevel nonvolatile memory devices with a floating gate consisting of hybrid organic/inorganic nanocomposites

Nonvolatile memory devices based on a poly(4-vinylphenol) (PVP) layer containing Cu2ZnSnS4 (CZTS) nanoparticles were fabricated by using a simple spin-coating method. An energy dispersive spectrum revealed that the CZTS nanoparticles were Cu poor and Zn rich. Transmission electron microscopy images showed that the CZTS nanoparticles were randomly distributed in the PVP layer. Capacitance–voltage (C–V) curves for Al/CZTS nanoparticles embedded in PVP layer/p-Si devices at 1MHz showed a hysteresis with flat-band voltage (Vfb) shifts, which resulted from the existence of CZTS nanoparticles acting as trap sites in the memory devices. The magnitudes of the Vfb corresponding to the memory window shifts between 1.0 and 2.5V, as determined from the C–V data at 1MHz, were dependent on the voltages applied to the memory device, indicative of multilevel characteristics for the memory effect. The operating mechanisms of the writing and the erasing processes for Al/CZTS nanoparticles embedded in PVP layer/p-Si devices are described on the basis of the C–V results and the energy-band diagrams.