Localized Storage Research Articles

Neural associative memory for brain modeling and information retrieval

This work concisely reviews and unifies the analysis of different variants of neural associative networks consisting of binary neurons and synapses (Willshaw model). We compute storage capacity, fault tolerance, and retrieval efficiency and point out problems of the classical Willshaw model such as limited fault tolerance and restriction to logarithmically sparse random patterns. Then we suggest possible solutions employing spiking neurons, compression of the memory structures, and additional cell layers. Finally, we discuss from a technical perspective whether distributed neural associative memories have any practical advantage over localized storage, e.g., in compressed look-up tables.

Two-bit SONOS type Flash using a band engineering in the nitride layer

A novel film in the trapping layer of SONOS device has been proposed. With gradually changing Si/N content ratio, the nitrogen-rich in middle (NRM) nitride has better performance and reliability than a conventional standard Si3N4film. This new configuration can increase trapping efficiency by adding the probability of lateral hopping and reduce charge loss tunneling back to substrate from nitride. Besides, the characteristics of the two-bit operation are exhibited in this study. The SONOS of NRM nitride is suitable for a localized trapping storage promising non-volatile memory application.

Positive Oxide Charge-Enhanced Read Disturb in a Localized Trapping Storage Flash Memory Cell

Read disturb-induced erase-state threshold voltage instability in a localized trapping storage Flash memory cell with a poly-silicon-oxide-nitride-oxide-silicon (SONOS) structure is investigated and reported. Our results show that positive trapped charge in bottom oxide generated during program/erase (P/E) cycles play a major role. Both gate voltage and drain voltage will accelerate the threshold voltage (V/sub t/) drift. Hot-carrier caused disturb effect is more severe in a shorter gate length device at low temperature. A model of positive charge-assisted electron tunneling into a trapping nitride is proposed. Influence of channel doping on the V/sub t/ drift is studied. As the cell is in an "unbiased" storage mode, tunnel detrapping of positive oxide charges is responsible for the threshold voltage shift, which is insensitive to temperature.

Lateral Distribution of Electrons Trapped in Nitride Layers

ABSTRACTThe recent advent of nitride-based localized charge-trapping storage has raised much interest in the lateral characterization of the trapped charge distribution, which is fundamental in defining scalability and retention properties. A direct characterization technique based on amplitude-sweep charge-pumping measurements is exploited here to investigate the lateral distribution of trapped electrons along the channel length. Further, the technique is applied to monitor the charge redistribution in time at high temperature.

An adaptive procedure for fracture simulation in extensive lattice networks

The potential for simulating fracture processes using lattice networks remains largely unrealized due to the computational expense associated with such approaches. The range of specimen sizes and mesh densities which can be practically explored is quite limited. This paper shows that, for localized fracture processes, both computing time and storage requirements can be greatly reduced by modeling only the fracture process zone and its immediate vicinity with a lattice network. The material surrounding the lattice work is represented using boundary elements and is assumed to be linear elastic. The model layout is updated as the fracture process evolves; updates are guided by a conventional fuzzy control scheme. Effectiveness of this adaptive procedure is shown through examples involving concrete fracture.

Leptomeningeal lipid storage patterns in Fabry disease.

We found two patterns of leptomeningeal storage that reflect two basic visceral storage patterns in Fabry disease. (i) A generalized-type leptomeningeal storage pattern, affecting all main leptomeningeal cell types (external arachnoideal epithelium, fibroblasts, vessel wall elements), was a consistent finding in three cases of classical generalized visceral phenotype. (ii) A localized leptomeningeal storage pattern was expressed, to a high degree, solely in the external arachnoidal epithelium; this pattern was found in one case with the variant visceral-restricted-type storage (confined to the cardiocytes). Thus, the external arachnoidal epithelium may be particularly susceptible to Fabry lipid storage, probably caused by a distinctly larger sustained lysosomal lipid load as compared to other cell types.

Phonon-absorption imaging of the electron-hole liquid in Ge

We report the use of heat pulses to image the spatial distribution of electron-hole liquid (EHL) produced by either cw or pulsed Nd: yttrium aluminum garnet laser excitation. The transmission of phonons through the EHL cloud is observed as the probe pulses are scanned in two dimensions. In contrast to previous phonon-absorption work, the scattering of the fast transverse-acoustic phonons ($\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}\ensuremath{\parallel}〈110〉$) is found to be quite strong. For cw clouds 2 mm in diameter, 35% of the probe phonons were scattered or absorbed. For the clouds excited by a high-energy $Q$-switched pulse, up to 60% of the phonon beam was attenuated. This is nearly all of the phonons which can satisfy energy and momentum conservation, indicating that the pulsed cloud has a much larger filling factor than that of a cw cloud. Interpretation of the large absorption requires the inclusion of hole-phonon scattering, which has not been previously considered. Time-resolved phonon-absorption images show that during the laser pulse the liquid expands at near-sonic velocity. After the pulse, electron-hole droplets are driven for millimeters by the action of a phonon wind, consistent with the results of recent luminescence studies. There is no evidence in the absorption profiles of a large, long-lived source of phonons (Hensel-Dynes hot spot). Additional time- and space-resolved heat-pulse experiments indicate that the long tail ($\ensuremath{\tau}=5\ensuremath{-}10$ \ensuremath{\mu}sec) in the heat-pulse signal is not due to localized storage of phonons. Instead it is ascribed to elastic and inelastic scattering of the phonons within the bulk of the sample.

Reduction of radiation induced soft error rates in devices utilizing localized state charge storage

It is shown that for semiconductor memory devices utilizing charge storage in localized states it is possible to achieve a high degree of immunity to soft errors. This is accomplished by the application of an electric field which is strong enough to efficiently remove carriers produced by radiation from the region where charge is stored in localized states but not so strong as to remove readily by field ionization charge already stored in localized states. Tests of this concept have been performed using energetic Compton electrons produced by gamma rays.

New magneto-optic memory concept based on compensation wall domains

A new concept of thermomagnetic localized reversible magneto-optic storage is proposed based on the application of compensation wall domains (CWD). Individual CWD's of 12 × 12-μm dimensions in an LPE film of composition Y2.34Gd0.52Yb0.14Fe3.74Ga1.26 O12 with 3-μm thickness have been switched by laser flashes of 10−2 erg/μm2 energy in 5 μs at 5145-Å wavelength using a stationary field of 41 Oe normal to the film plane.

Carrier transport and storage effects in Au ion implanted SiO 2 structures

To investigate the possibility of fabricating a multilayer gate IGFET using an ion implanted floating electrode, an MOS structure has been made using thermally grown SiO 2 layers into which 100 keV Au + ions were implanted. The effects of ion dose (10 12–10 14 cm −2) oxide thickness (500–1000 Å), and post implantation annealing treatment on the capacitance-voltage and current-voltage characteristics were studied. A significant flatband voltage shift is observed for ion doses larger than 10 13 cm −2. Most of the interface states created by the implantation damage anneal at 400°C ( ss ∼ 10 10 cm −2 for oxide thickness 750 Å). The carrier transport mechanism of the implanted SiO 2 layer is converted from Fowler-Nordheim tunneling conduction to Frenkel-Poole bulk conduction with a trapping energy level 1·2 eV below the oxide conduction band. From these mechanisms the flatband voltage shift due to electrons trapped at assumed localized Au charge storage centers is predicted. This reversible shift is experimentally confirmed by C- V measurements. The time required for a 1 V flatband shift is about 10 −3 sec when a field of 10 7 V/cm is applied. Thus the resulting MOS structure behaves similarly to a floating gate or multilayer device with obvious simplifications in the processing. It is believed that improvements in reducing the charging time and the writing voltage may be realized by the use of thinner oxides in conjunction with lower implantation energies.

Trace Localization and the Recognition of Visual Form

In the first of three experiments, previous research by Wallach and Austin suggesting localized storage of visual traces was replicated, using new stimulus materials. In the second, an alternative hypothesis accounting for trace selection by phenomenal, rather than anatomical, locus was examined and rejected. In the third, the possibility that eye-movement tendencies may provide mediating stimuli that govern trace selection was explored, with negative results. The hypothesis of differential trace localization originally put forth by Wallach and Austin remains the most economical explanation of their results, but neither their research nor the present experiments indicate whether the localized trace is best described as a template or as a set of features. In 1954, Wallach and Austin reported an experiment on visual recognition the results of which, they believed, indicated that memory traces of visual stimuli are localized in a cortical region specific to the region of original excitation.' The experiment hinged upon the use of a silhouette figure which when viewed in one orientation represented a man wearing a chef's hat, but when rotated 90 deg. to one side represented a dog. The chef, the dog, and seven other silhouettes were shown one at a time tachistoscopically, and the observer was required to identify them. Each figure appeared in one of four quadrants of the projection screen, with the observer fixating the center point during the exposure. The two versions of the critical figure were shown second and sixth in the series, one to the upper left and one to the upper right of the fixation point. As a tenth and final figure, the critical figure was again presented in either the upper left or upper right quadrant, but oriented diagonally so as to constitute an 'ambiguous' figure. Of the 48 observers who completed the experiment, 36 responded Received for publication by Professor E. B. Newman. The author thanks Steven J. Taff for his assistance in conducting the experiments and Richard V. Schultz for help in preparing slides for Experiments I and II. 1 Hans Wallach and Pauline Austin, Recognition and the localization of visual traces, this JOURNAL, 67, 1954, 338-340.