Two-Silicon-Nanocrystal Layer Memory Structure with Improved Retention Characteristics

2007 ◽  
Vol 7 (1) ◽  
pp. 368-373 ◽  
Author(s):  
A. G. Nassiopoulou ◽  
A. Salonidou
Keyword(s):  
Silicon Nanocrystals ◽  
Gate Dielectric ◽  
Lower Layer ◽  
Layer Structure ◽  
Use Of Self ◽  
First Case ◽  
Layer Structures ◽  
Charge Loss ◽  
Retention Characteristics ◽  
Nanocrystal Memory

It was demonstrated in the literature that the use of self-aligned doubly-stacked Si dots improves retention characteristics of a nanocrystal memory. In this paper, we show that a similar effect may be obtained by using two distinct layers of silicon nanocrystals within the gate dielectric of the MOS structure, if the nanocrystal density in each layer is high enough (above 1012 dots/cm2) so as to get an average effect of at least one smaller dot underneath each larger one. The relative distance of the layers and their position from the silicon substrate and the gate metal are critical for optimum memory operation. Two different double-nanocrystal-layer structures were investigated. In the first structure the two nanocrystal layers were close together and they were composed of dots of different size (lower layer: 3 nm, upper layer: 5 nm), while in the second structure the dot layers were composed of dots of equal diameter (d = 3 nm) and their inter-distance was much larger. In both cases, the retention characteristics of the structure were improved compared with a single dot layer structure. In the second case this improvement was significantly larger than in the first case. Extrapolation of the data to ten years memory operation, showed that the charge loss after this time was only ≈ 12%.

scholarly journals Fabrication of Piezoelectric ZnO Nanowires Energy Harvester on Flexible Substrate Coated with Various Seed Layer Structures

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1433
Author(s):  
Taoufik Slimani Tlemcani ◽  
Camille Justeau ◽  
Kevin Nadaud ◽  
Daniel Alquier ◽  
Guylaine Poulin-Vittrant
Keyword(s):  
Seed Layer ◽  
Layer Structure ◽  
Mechanical Energy ◽  
Flexible Substrate ◽  
Average Power ◽  
Electrical Characterization ◽  
Zno Nanowires ◽  
Device Structure ◽  
Layer Structures ◽  
Electrical Output

Flexible piezoelectric nanogenerators (PENGs) are very attractive for mechanical energy harvesting due to their high potential for realizing self-powered sensors and low-power electronics. In this paper, a PENG that is based on zinc oxide (ZnO) nanowires (NWs) is fabricated on flexible and transparent Polydimethylsiloxane (PDMS) substrate. The ZnO NWs were deposited on two different seed layer structures, i.e., gold (Au)/ZnO and tin-doped indium-oxide (ITO)/ZnO, using hydrothermal synthesis. Along with the structural and morphological analyses of ZnO NWs, the electrical characterization was also investigated for ZnO NWs-based flexible PENGs. In order to evaluate the suitability of the PENG device structure, the electrical output performance was studied. By applying a periodic mechanical force of 3 N, the ZnO NWs-based flexible PENG generated a maximum root mean square (RMS) voltage and average power of 2.7 V and 64 nW, respectively. Moreover, the comparison between the fabricated device performances shows that a higher electrical output can be obtained when ITO/ZnO seed layer structure is adopted. The proposed ZnO NWs-based PENG structure can provide a flexible and cost-effective device for supplying portable electronics.

Restricted Rotational Motion of InterlayerWaterMolecules in Vanadium Pentoxide Hydrate, V2O5·n D2O, as Studied by Deuterium NMR

2002 ◽  
Vol 57 (6-7) ◽  
pp. 419-424 ◽  
Author(s):  
Sadamu Takeda ◽  
Yuko Gotoh ◽  
Goro Maruta ◽  
Shuichi Takahara ◽  
Shigeharu Kittaka
Keyword(s):  
Double Layer ◽  
Vanadium Pentoxide ◽  
Rotational Motion ◽  
Interlayer Space ◽  
Layer Structure ◽  
Bond Distance ◽  
Adsorbed Water ◽  
Deuterium Nmr ◽  
Water Molecules ◽  
Layer Structures

The rotational behavior of the interlayer water molecules of deuterated vanadium pentoxide hydrate, V2O5.nD2O, was studied by solid-state deuterium NMR for the mono- and double-layer structures of the adsorbed water molecules. The rotational motion was anisotropic even at 355 K for both the mono- and double-layer structures. The 180° flipping motion about the C2-symmetry axis of the water molecule and the rotation around the figure axis, which makes an angle Ɵ with the C2-axis, occurred with the activation energy of (34±4) and (49±6) kJmol-1, respectively. The activation energies were almost independent of the mono- and double-layer structures of the water molecules, but the angle Ɵ made by the two axes varied from 33° for the monolayer to 25° for the double-layer at 230 K. The angle started to decrease above 250 K (e. g. the angle was 17 at 355 K for the double-layer structure). The results indicate that the average orientation of the water molecules in the two dimensional interlayer space depends on the layer structure and on the temperature. From the deuterium NMR spectrum at 130 K, the quadrupole coupling constant e2Qq/h = 240 kHz and the asymmetry parameter η= 0.12 were deduced. These values indicate the average hydrogen bond distance R(O H) = 2.0 Å for the D2O molecules in the 2D-interlayer space

Crystal Structures of Seven Terephthaldiamide Derivatives

2002 ◽  
Vol 57 (8) ◽  
pp. 914-921 ◽  
Author(s):  
P. G. Jones ◽  
J. Ossowski ◽  
P. Kus
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Layer Structure ◽  
Inversion Symmetry ◽  
Asymmetric Unit ◽  
X Ray ◽  
Layer Structures ◽  
Structure Determinations ◽  
Independent Molecules

N,N′-Dibutyl-terephthaldiamide (1), N,N′-dihexyl-terephthaldiamide (2), N,N′-di(tert-butyl)- terephthaldiamide (3), N,N,N′,N′-tetrabutyl-terephthaldiamide (4), 1,1′-terephthaloylbis- pyrrolidine (5), 1,1′-terephthaloyl-bis-piperidine (6), and 4,4′-terephthaloyl-bis-morpholine (7) have been synthesised and physicochemically characterised. The X-ray structure determinations reveal imposed inversion symmetry for compounds 1-6; compound 3 has two independent molecules with inversion symmetry in the asymmetric unit. Compounds 1-3 form classical hydrogen bonds of the type N-H···O=C, leading to a ribbon-like arrangement of molecules (1 and 2) or a layer structure (3). Compound 3 also displays a very short C-H···O interaction, a type of hydrogen bond that is also observed in compounds 4-7, which lack classical donors; thereby compounds 4-6 form layer structures and 7 a complex threedimensional network.

scholarly journals Mechanics for the Adhesion and Aggregation of Red Blood Cells on Chitosan

2018 ◽  
Vol 34 (5) ◽  
pp. 725-732 ◽  
Author(s):  
K. Y. Chen ◽  
T. H. Lin ◽  
C. Y. Yang ◽  
Y. W. Kuo ◽  
U. Lei
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Biomedical Applications ◽  
Adhesion Force ◽  
Layer Structure ◽  
Optical Tweezer ◽  
Wound Dressings ◽  
Zeta Potentials ◽  
Rbc Membrane ◽  
Layer Structures

AbstractHemostasis, a process which causes bleeding to stop, can be enhanced using chitosan; but the detailed mechanism is unclear. Red blood cells (RBCs) adhere to chitosan because of their opposite charges, but the adhesion force is small, 3.83 pN as measured here using an optical tweezer, such that the direct adhesion cannot be the sole cause for hemostasis. However, it was observed in this study that layer structures of aggregated RBCs were formed next to chitosan objects in both static and flowing environments, but not formed next to cotton and rayon yarns. The layer structure is the clue for the initiation of hemostatsis. Through the supporting measurements of zeta potentials of RBCs and pH's using blood-chitosan mixtures, it is proposed here that the formation of the RBC layer structure next to chitosan objects is due to the reduction of repulsive electric double layer force between RBCs, because of the association of H+ deprotonated from chitosan with COO− on RBC membrane, under the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. The results are beneficial for designing effective chitosan-based wound dressings, and also for general biomedical applications.

scholarly journals Rotational symmetry of photonic bound states in the continuum

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Liangsheng Li ◽  
Yunzhou Li ◽  
Yong Zhu ◽  
Hongcheng Yin
Keyword(s):  
Photonic Crystal ◽  
Bound States ◽  
Layer Structure ◽  
Rotational Symmetry ◽  
Coupled Model ◽  
Numerical Data ◽  
Life Time ◽  
Layer Structures ◽  
Radiation Decay ◽  
The Continuum

Abstract The bound states in the continuum (BICs) have been investigated by simulating the optical reflectivity of a tri-layer photonic crystal slab. We found that optical BICs can occur in a class of photonic crystal systems with $$c_{1}^{z}$$ c 1 z , $$c_{2}^{z}$$ c 2 z or $$c_{4}^{z}$$ c 4 z rotational symmetries, which are constructed by three identical photonic crystal slabs. By applying the two mode coupled model, we obtain the reflectivity formula to fit the numerical data and evaluate the lifetime of radiation decay. In vicinity of BIC, the lifetime diverges as a power law form, when approaching the BIC point. The infinity life time of $$c_{1}^{z} {\text{ } - \text{ BIC}}$$ c 1 z - BIC in the tri-layer structure indicate that it is a true BIC. The $$c_{1}^{z} {\text{ } - \text{ BIC}}$$ c 1 z - BIC occurs robustly in tri-layer structures, but the resonance frequency of the BICs is dependent on the permittivity of slab, air-hole size and hole shape.

scholarly journals Double-layer structure in polar mesospheric clouds observed from SOFIE/AIM

2017 ◽  
Vol 35 (2) ◽  
pp. 295-309 ◽  
Author(s):  
Haiyang Gao ◽  
Gordon G. Shepherd ◽  
Yuanhe Tang ◽  
Lingbing Bu ◽  
Zhen Wang
Keyword(s):  
Double Layer ◽  
Lower Layer ◽  
Layer Structure ◽  
Polar Mesospheric Clouds ◽  
Double Peaks ◽  
Double Layer Structure ◽  
Ice Water Content ◽  
Background Temperature ◽  
Mesospheric Clouds ◽  
Ice Water

Abstract. Double-layer structures in polar mesospheric clouds (PMCs) are observed by using Solar Occultation for Ice Experiment (SOFIE) data between 2007 and 2014. We find 816 and 301 events of double-layer structure with percentages of 10.32 and 7.25 % compared to total PMC events, and the mean distances between two peaks are 3.06 and 2.73 km for the Northern Hemisphere (NH) and Southern Hemisphere (SH) respectively. Double-layer PMCs almost always have less mean ice water content (IWC) than daily IWC during the core of the season, but they are close to each other at the beginning and the end. The result by averaging over all events shows that the particle concentration has obvious double peaks, while the particle radius exhibits an unexpected monotonic increase with decreasing altitude. By further analysis of the background temperature and water vapour residual profiles, we conclude that the lower layer is a reproduced one formed at the bottom of the upper layer. 56.00 and 47.51 % of all double-layer events for the NH and SH respectively have temperature enhancements larger than 2 K locating between their double peaks. The longitudinal anti-correlation between the gravity waves' (GWs') potential energies and occurrence frequencies of double-layer PMCs suggests that the double-layer PMCs tend to form in an environment where the GWs have weaker intensities.

Two polymorphs and the diethylammonium salt of the barbiturate eldoral

2012 ◽  
Vol 68 (2) ◽  
pp. o65-o70 ◽  
Author(s):  
Thomas Gelbrich ◽  
Denise Rossi ◽  
Ulrich J. Griesser
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Barbituric Acid ◽  
Layer Structure ◽  
Chain Structure ◽  
Hydrogen Bond Acceptor ◽  
Layer Structures ◽  
A Chain ◽  
Derivatives Of ◽  
Hydrogen Bonded

Polymorph (Ia) of eldoral [5-ethyl-5-(piperidin-1-yl)barbituric acid or 5-ethyl-5-(piperidin-1-yl)-1,3-diazinane-2,4,6-trione], C11H17N3O3, displays a hydrogen-bonded layer structure parallel to (100). The piperidine N atom and the barbiturate carbonyl group in the 2-position are utilized in N—H...N and N—H...O=C hydrogen bonds, respectively. The structure of polymorph (Ib) contains pseudosymmetry elements. The two independent molecules of (Ib) are connectedviaN—H...O=C(4/6-position) and N—H...N(piperidine) hydrogen bonds to give a chain structure in the [100] direction. The hydrogen-bonded layers, parallel to (010), formed in the salt diethylammonium 5-ethyl-5-(piperidin-1-yl)barbiturate [or diethylammonium 5-ethyl-2,4,6-trioxo-5-(piperidin-1-yl)-1,3-diazinan-1-ide], C4H12N+·C11H16N3O3−, (II), closely resemble the corresponding hydrogen-bonded structure in polymorph (Ia). Like many other 5,5-disubstituted derivatives of barbituric acid, polymorphs (Ia) and (Ib) contain theR22(8) N—H...O=C hydrogen-bond motif. However, the overall hydrogen-bonded chain and layer structures of (Ia) and (Ib) are unique because of the involvement of the hydrogen-bond acceptor function in the piperidine group.

Future Silicon Nanocrystal Nonvolatile Memory Technology

2001 ◽  
Vol 686 ◽  
Author(s):  
Michele L. Ostraat ◽  
Jan W. De Blauwe
Keyword(s):  
Threshold Voltage ◽  
Flash Memory ◽  
Nonvolatile Memory ◽  
Gate Dielectric ◽  
Oxide Thickness ◽  
Channel Length ◽  
Charge Storage ◽  
Memory Devices ◽  
Two Stage ◽  
Nanocrystal Memory

AbstractA great deal of research interest is being invested in the fabrication and characterization of nanocrystal structures as charge storage memory devices. In these flash memory devices, it is possible to measure threshold voltage shifts due to charge storage of only a few electrons per nanocrystal at room temperature. Although a variety of methods exist to fabricate nanocrystals and to incorporate them into device layers, control over the critical nanocrystal dimensions, tunnel oxide thickness, and interparticle separation and isolation remains difficult to achieve. This control is vital to produce reliable and consistent devices over large wafer areas. To address these control issues, we have developed a novel two-stage ultra clean reactor in which the Si nanocrystals are generated as single crystal, nonagglomerated, spherical aerosol particles from silane decomposition at 950°C at concentrations exceeding 108 cm−3 at sizes below 10 nm. Using existing aerosol instrumentation, it is possible to control the particle size to approximately 10% on diameter. In the second reactor, particles are passivated with a high quality oxide layer with shell thickness controllable from 0.7 to 2.0 nm. The two-stage aerosol reactor is integrated to a 200 mm wafer deposition chamber such that controlled particle densities can be deposited thermophoretically. With nanocrystal deposits of 1013 cm−2, contamination of transition metals and other elements can be controlled to less than 1010 atoms cm−2.We have fabricated 0.2 μm channel length aerosol nanocrystal floating gate memory devices using conventional MOS ULSI processing on 200 mm wafers. The aerosol nanocrystal memory devices exhibit normal transistor characteristics with drive current 30 μA/μm, subthreshold slope 200 mV/dec, and drain induced barrier lowering 100 mV/V, typical values for thick gate dielectric high substrate doped nonvolatile memory devices. Uniform Fowler-Nordheim tunneling is used to program and erase these memory devices. Despite 5 nm tunnel oxides, threshold voltage shifts > 2 V have been achieved with microsecond program and millisecond erase times at moderate operating voltages. The aerosol devices also exhibit excellent endurance cyclability with no window closure observed after 105 cycles. Furthermore, reasonable disturb times and long nonvolatility are obtained, illustrating the inherent advantage of discrete nanocrystal charge storage. No drain disturb was detected even at drain biases of 4V, indicating that little or no charge conduction occurs in the nanocrystal layer. We have demonstrated promise for aerosol nanocrystal memory devices. However, numerous issues exist for the future of nanocrystal devices. These technology issues and challenges will be discussed as directions for future work.

Dynamic Mechanical Property of Quasi Constrained Layer Structural Piezoelectric Ceramic/Carbon Black/Epoxy Resin Composites

2011 ◽  
Vol 284-286 ◽  
pp. 429-433
Author(s):  
Wen Chao Huang ◽  
Tao Wei ◽  
Min Xian Shi
Keyword(s):  
Carbon Black ◽  
Epoxy Resin ◽  
Piezoelectric Ceramic ◽  
Volume Fraction ◽  
Layer Structure ◽  
Polymeric Composite ◽  
Mechanical Analysis ◽  
Constrained Layer Damping ◽  
Dynamic Mechanical ◽  
Layer Structures

Two-step casting method was developed for preparing quasi constrained layer damping structural polymeric composite. Quasi constrained layer structural piezoelectric ceramic P82/carbon black(CB)/epoxy resin(EP) composites were successfully prepared when the ceramic content was less than 30% in volume. Dynamic mechanical analysis(DMA) showed that the composites with quasi constrained layer structure exhibited perfect damping properties. When the piezoelectric ceramic P82 volume fraction was 10%, the composite showed the highest loss factor peak value of 1.182, the widest damping temperature range of 44.2°C, and the largest loss area of 32.17. The storage moduli of composites with quasi constrained layer structures were higher than that with non quasi constrained layer structure.

Single-Crystal Thin Films of SrFeO2 and LaNiO2 with Infinite-Layer Structures

2008 ◽  
Vol 1148 ◽  
Author(s):  
Yuichi Shimakawa ◽  
Satoru Inoue ◽  
Masanori Kawai ◽  
Noriya Ichikawa ◽  
Masaichiro Mizumaki ◽  
...  
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Layer Structure ◽  
Reduction Process ◽  
Transition Metal Ions ◽  
Epitaxial Thin Films ◽  
Infinite Layer ◽  
Oxygen Ions ◽  
Structure Framework ◽  
Layer Structures

AbstractInfinite-layer-structure epitaxial thin films of SrFeO2 and LaNiO2 respectively were prepared by low-temperature reduction with CaH2 from brownmillerite SrFeO2.5 and perovskite LaNiO3 epitaxial thin films grown on single-crystal substrates. The reduction process, removing oxygen ions from the perovskite-structure framework and causing rearrangements of oxygen ions, topotactically transforms the initial compounds to the c-axis oriented infinite-layer-structure epitaxial thin films. Consequently, the oxidation state of transition-metal ions in the film changed in wide ranges.

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