We describe a versatile approach for preparing flash memory devices composed of polyelectrolyte/gold nanoparticle multilayer films. Anionic gold nanoparticles were used as the charge storage elements, and poly(allylamine)/poly(styrenesulfonate) multilayers deposited onto hafnium oxide (HfO2)-coated silicon substrates formed the insulating layers. The top contact was formed by depositing HfO2 and platinum. In this study, we investigated the effect of increasing the number of polyelectrolyte and gold nanoparticle layers on memory performance, including the size of the memory window (the critical voltage difference between the 'programmed' and 'erased' states of the devices) and programming speed. We observed a maximum memory window of about 1.8 V, with a stored electron density of 4.2 x 1012 cm-2 in the gold nanoparticle layers, when the devices consist of three polyelectrolyte/gold nanoparticle layers. The reported approach offers new opportunities to prepare nanostructured polyelectrolyte/gold nanoparticle-based memory devices with tailored performance.

trolled using a closed-cycle Helium cryostat (Cryogenic Technology Inc., model 501A).Theoretical Methodology: The geometry of all compounds was fully optimized with the semiempirical PM3 (Parametric Method 3) Hamiltonian [26], which yields a coplanar structure. The vibrational frequencies were also computed at this level of theory and confirm the global minimum of the equilibrium geometry by the absence of negative frequencies. The geometric relaxation taking place in the lowest excited state has been described by coupling the PM3 method to a full CI (configuration interaction) expansion involving a limited number of orbitals (as implemented in the AMPAC package) [27]. The size of the CI active space is chosen in order to ensure the convergence of the geometric parameters. On the basis of the PM3-optimized structures, the transition energy and transition dipole moment associated to the lowest excited state of the compounds have been estimated with the help of the spectroscopic version of the semiempirical These efforts span not only layer-structured materials, but also metallic, semiconducting, and even strongly ionic bonded oxide materials. The latter, however, have often been found as nanosized tubular materials. Nanotubes and/or nanotubular oxide (and, in particular, functional oxide) materials that have particularly promising physical properties and potential applications in nanoelectronics, however, are rarely found or synthesized. Nanotubes of SiO 2 , TiO 2 , and vanadium oxides have been synthesized, using several different processing techniques. Among these, nanotubes of TiO 2 have been the most intensively investigated, since their superior catalytic properties are combined with nanotubular forms of high surface area. Much effort has been devoted to forming TiO 2 nanotubes, and nanotubular COMMUNICATIONS

Tremendous effort has been made toward the development of high-density, low-cost, and nonvolatile solid-state storage devices for use in portable electronic devices such as MP3 players, mobile phones, and digital cameras. [1][2][3][4][5][6][7][8][9][10][11] Among the many types of nonvolatile memory technology, flash memory devices with discrete charge-trapping layers, such as silicon-oxide-nitrideoxide-silicon (SONOS) devices or nanocrystal (NC)-based memory devices, are of great interest to the electronics industry, because of their better endurance, smaller chip size, and lower power consumption compared with floating-gate devices. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] Recently, Samsung Electronics successfully fabricated a 64-gigabit density SONOS-type flash memory device using Si 3 N 4 as a charge-trap layer.[26] However, it is very difficult to control the trap density and distribution in SONOS devices, although these parameters are quite important in determining the memory characteristics, especially the programmed/erased bit distribution and data retention. Thus, NC memory devices using metallic NCs as a charge-trapping layer have an advantage when it comes to controlling the trap density and distribution, because the density and location of the NCs can be controlled by adjusting the process parameters. Considerable work has focused on the controlled synthesis of semiconducting or metallic nanoparticles for use in nonvolatile memory devices. [16][17][18][19][20][21][22][23][24][25] Recently, we report that ordered arrays of metallic nanoparticles by a micellar route and multilayered metallic nanoparticles can be used as chargestorage media for nonvolatile memory devices with tailored performances. [24,25] However, most of the research on nanoparticle-based memory devices has been focused on the use of elemental metal nanoparticles as a charge trapping layer. Herein, we report for the first time the use of a controlled binary mixture of metal nanoparticles for the purpose of tuning the memory characteristics in charge-trap flash memory devices with i) a comparative and systematic study of the charging/discharging behaviors, ii) an analysis of the different charge trapping mechanisms according to the type of metal nanoparticle being used, iii) nanoscale device performance characterization using Kelvin force microscopy (KFM), and iv) tunable memory performances and applications to multilevel data storage. Figure 1 shows a schematic illustration of the memory architectures and storage element configurations. Elemental metal nanoparticles of Co and Au and a binary mixture thereof were used as the charge-trapping layers in the memory devices. A sputter-deposited HfO 2 layer was used both as a tunneling and blocking oxide layer. This type of device is based on the charge carrier transfer between the Si substrate and the charge trapping layer via the tunneling oxide (nominal thickness of 5 nm) by using a field effect. A thick blocking oxide layer (nominal thickness of 15 nm) is used to prevent ...

Significant potential of electronic textiles for wearable applications has triggered active studies of luminescent fibers toward smart textile displays. In spite of notable breakthroughs in the lighting fiber technology, a class of information displays with a luminescent fiber network is still underdeveloped due to several formidable challenges such as limited electroluminescence fiber performance, acute vulnerability to chemical and mechanical factors, and lack of decent engineering schemes to form fibers with robust interconnectable pixels for two-dimensional matrix addressing. Here, we present a highly feasible strategy for organic light-emitting diode (OLED) fiber-based textile displays that can overcome these issues by implementing prominent solution options including compatible fabrication method of OLED pixel arrays on adapted fiber configurations and chemically/mechanically sturdy but electrically conductive passivation system. To create solid interconnectable OLED fibers without compromising the high electroluminescence performance, phosphorescence OLED materials are deposited onto process-friendly fibers of rectangular stripes, where periodically patterned OLED pixels are selectively passivated with robust polymer and circumventing metal pads by a stamp-assisted printing method. A woven textile of interlaced interconnectable OLED fibers with perpendicularly arranged conductive fibers serves as a matrix-addressable two-dimensional network that can be operated by the passive matrix scheme. Successful demonstrations of stably working woven OLED textile in the water, as well as under the applied tensile force, support feasibility of the present approach to reify fully addressable, environmentally durable, fiber-based textile displays.

Pt-based bimetallic nanoparticles have attracted significant attention as a promising replacement for expensive Pt nanoparticles. In the systematic design of bimetallic nanoparticles, it is important to understand their preferred atomic structures. However, compared with unary systems, alloy nanoparticles present more structural complexity with various compositional configurations, such as mixed-alloy, core-shell, and multishell structures. In this paper, we developed a unified empirical potential model for various Pt-based binary alloys, such as Pd-Pt, Cu-Pt, Au-Pt, and Ag-Pt. Within this framework, we performed a series of Monte Carlo (MC) simulations that quantify the energetically favorable atomic arrangements of Pt-based alloy nanoparticles: an intermetallic compound structure for the Pd-Pt alloy, an onion-like multi-shell structure for the Cu-Pt alloy, and core-shell structures (Au@Pt and Ag@Pt) for the Au-Pt and Ag-Pt alloys. The equilibrium nanoparticle structures for the four alloy types were compared with each other, and the structural features can be interpreted by the interplay of their material properties, such as the surface energy and heat of formation. PACS numbers: 61.46.+w, 36.40.Ei, 64.70.Nd I. II. INTERATOMIC POTENTIAL MODEL A. Embedded atom method potentials for Pt, Pd, and novel metals (Ag, Au, Cu)