An in situ transmission electron microscopy ͑TEM͒ analysis of a solid electrolyte, Cu-GeS, during resistance switching is reported. Real-time observations of the filament formation and disappearance process were performed in the TEM instrument and the conductive-filament-formation model was confirmed experimentally. Narrow conductive filaments were formed corresponding to resistance switching from high-to low-resistance states. When the resistance changed to high-resistance state, the filament disappeared. It was also confirmed by use of selected area diffractometry and energy-dispersive x-ray spectroscopy that the conductive filament was made of nanocrystals composed mainly of Cu. Cu-SiO 2 , 12 and bilayer-types. 13,14 The mechanism of resistance switching is attributed to the formation and disappearance of the conductive filament in the solid electrolyte. When a bias voltage is applied, the ions generated at the anode are thought to migrate toward the cathode where they undergo reduction and become metal atoms. 8 Contrarily, an opposite bias voltage dissolves the metal composing filaments into the solid electrolyte.11 Therefore, an analysis of the conductive filament must provide important information for understanding this switching mechanism. Recently, conductive filament, which is formed in not only cation-type but also in aniontype electrolytes, was observed by scanning electron microscopy ͑SEM͒. 5,15,16 However, no detailed experimental results to confirm the existence of the filament during the switching process have been reported. Therefore, in situ transmission electron microscopy ͑TEM͒ with simultaneous electrical measurements has attracted a great deal of attention. 10,[17][18][19][20][21] In this letter, we use this in situ TEM method to reveal the switching mechanism of a solid electrolyte. Real-time observations of the filament formation and disappearance process were performed with the TEM instrument. We also clarified the structure and composition of the filament by the use of selected area diffractometry ͑SAD͒ and energydispersive x-ray spectroscopy ͑EDX͒.For the in situ TEM experiments, 21 commercially available Pt-Ir tips for scanning tunneling microscopy were further sharpened by ion milling. One Pt-Ir tip was used as the substrate and the other was used as a counter electrode. CuGeS thin films were deposited at room temperature by rf sputtering on Pt-Ir substrate. Since the substrate and the counter electrode of Pt-Ir were different in shape, the structure of Pt-Ir/Cu-GeS/Pt-Ir was asymmetric. The atomic composition of the sample layer was analyzed by means of EDX. The proportion of Cu:Ge:S was 4:4:2. The film thickness was between 8 and 60 nm, and no remarkable difference depending on thickness was recognized. The system was composed of a custom-made TEM holder with a PCcontrolled operating system. [21][22][23] The TEM instrument used mainly was a JEM-2010 microscope ͑200 kV, C s = 0.5 mm͒, having a vacuum of about 10 −5 Pa. The conduction properties were measured between the Pt-Ir counter...

t-Bu),BzN(O)nitrobenzyl bromide, 100-11-8; p-nitrobenzyl duryl nitrodide, 84802-29-9; methyl iodide, 74-88-4; N-methyl-N-tris(tert-bu-ty1)phenyl nitroxide radical, 33721-34-5; N-methoxy-N-tris-(tert-buty1)phenyl anilino radical, 64191-72-6; benzyl bromide, electrochemical cell. CHZ(CBHJNO2,,BzN(O)H,The nitrate radical, NO3, was directly detected by the laser-induced fluorescence method. The band structure of the fluorescence excitation spectrum was consistent with that of the absorption spectrum. The fluorescence spectrum excited at 662 nm corresponding to the 0-0 transition showed progressions with 1060-and 1480-cm-' intervals, which were assigned to the symmetric stretching (vl) and degenerate antisymmetric stretching (v3) modes of the ground state NO,, respectively. The fluorescence lifetime excited at the 0-0 band was estimated to be 2.8 ~s from the Stern-Volmer plots in the pressure region of 0.04-0.6 torr.(9) J. R. McDonald, private communication. Geophys. Res. Lett., 7 , 89 (1980).Perturbations around steady states of a system of cerium or manganese bromide and bromate ions in a sulfuric acid solution, in a continuous stirred tank reactor (CSTR), are investigated. Two kinds of perturbations are discussed, namely, small-species and large-constraint ones. The feasibility of measuring a particular rate constant by following the system behavior after a small perturbation is analyzed. Some general theorems regarding this behavior are obtained. Large perturbations, namely, those that cause a transition of the system from one steady state to another, are analyzed and an approximate relationship between the perturbations' intensity and length is developed. The results are in good agreement with the experimental data.

in irradiations with bremsstrahlung having maximum end-point energies up to 1200 MeV were measured by γ-ray spectrometry ( 7 Be, 22 Na, 24 Na and 28 Mg) and accelerator mass spectrometry ( 10 Be). The yields of heavier fragments, 39 Cl,43, 44m, 44g,46,47, 48 Sc, 59 Fe,and 56,57,58,60 Co, were also measured by γ-ray spectrometry in order to survey the relative contribution of fragmentation to spallation and/or fission in the mass yield curves. A distinct difference of the target massdependence of these yields has made it possible to disentangle the contributions of photospallation and photofragmentation processes. It was found that the neutron-to-proton ratios of targets strongly affect the formation of the nuclei by fragmentation as revealed in the yields of the isotopic pairs as well as of the single isotopes. The photon results were compared with those of proton-induced reactions, and no clear effect due to the difference of the initial interactions of photons and protons with nuclei was found in the fragment yields.

Yields of 24 radioactive nuclides formed by the interaction of bremsstrahlung with maximum end-point energies of 100 MeV -1 GeV with Cu have been measured by direct y-ray counting of irradiated targets. The yields in the mass range of 42 to 60 (except for Cu) were analyzed by a nonlinear least-squares fit to obtain the mass yield and charge dispersion curves in spallation reactions.From the parameter values obtained, the energy dependence of the slope of the mass yield curve and the relationship between target N/Z and the most probable product N/Z were investigated and compared with the results of proton, a, and heavy-ion-induced spallation of Cu. The characteristics of photon-induced spallation are discussed.

The energy level, density and attempt to escape frequency of carrier traps in an Si3N4 film in tunnel oxide/nitride/oxide (ONO) multilayer for metal/oxide/nitride/oxide/silicon (MONOS) nonvolatile memory are investigated by discharging current transient spectroscopy (DCTS). To analyze the electrical properties of carrier traps observed through DCTS, a new model including the tunneling probability of the tunnel oxide film between the Si3N4 film and an Si substrate was proposed. As a result, the electron traps in the Si3N4 film, which are assumed to be related to the threshold voltage decay, i.e. data retention, were found for the first time. The energy level of the electron traps in the Si3N4 film in the ONO multilayer was 0.8–0.9 eV from the conduction band and the density was 1–5×1018 cm-3. The attempt to escape frequency of 2×1014 s-1 was also obtained. The energy level of the hole traps and its density were 0.8–0.9 eV from the top of the valence band and 1–4×1018 cm-3, respectively. The magnitude of the trap density obtained from DCTS shows good agreement with that obtained from memory hysteresis characteristics. These results indicate that their carrier traps are amphoteric traps.