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The magnetic and microwave absorption properties of the interstitial atom modified intermetallic compound Ce2Fe17NX have been investigated. The Ce2Fe17NX compound shows a planar anisotropy with saturation magnetization of 1088 kA/m at room temperature. The Ce2Fe17NX paraffin composite with a mass ratio of 1:1 exhibits a permeability of μ' = 2.7 at low frequency, together with a reflection loss of - 26 dB at 6.9 GHz with a thickness of 1.5 mm and - 60 dB at 2.2 GHz with a thickness of 4.0 mm. It was found that this composite increases the Snoek limit and exhibits both high working frequency and permeability due to its high saturation magnetization and high ratio of the c-axis anisotropy field to the basal plane anisotropy field. Hence, it is possible that this composite can be used as a high-performance thin layer microwave absorber. [ABSTRACT FROM AUTHOR]

A memory device p-Si/SiO2/(TiO2)0.8(Al2O3)0.1(TAO-81)/Al2O3/Pt was fabricated, in which a composite of two high-k dielectrics with a thickness of 1 nm was employed as the charge-trapping layer to enhance the charge-trapping efficiency of the memory device. At an applied gate voltage of ±9V, TAO-81 memory device shows a memory window of 8.83V in its C-V curve. It also shows a fast response to a short voltage pulse of 10-5 s. The charge-trapping capability, the endurance, and retention characteristics of TAO-81 memory device can be improved by introducing double TAO-81 charge-trapping layers intercalated by an Al2O3 layer. The charge-trapping mechanism in the memory device is mainly ascribed to the generation of the electron-occupied defect level in the band gap of Al2O3 induced by the inter-diffusion between TiO2 and Al2O3. [ABSTRACT FROM AUTHOR]

We report on the properties of semipolar (Zn,Mg)O/ZnO quantum wells homoepitaxially grown by molecular beam epitaxy on [formula] R-plane ZnO substrates. We demonstrate that atomically flat interfaces can be achieved with fully relaxed quantum wells because the mismatch between (Zn,Mg)O and ZnO is minimal for this growth orientation. The photoluminescence properties evidence a quantum confined Stark effect with an internal electric field estimated to 430 kV/cm for a 17% Mg content in the barriers. The quantum well emission is strongly polarized along the [formula] direction and a comparison with the semipolar bulk ZnO luminescence polarization points to the effect of the confinement. [ABSTRACT FROM AUTHOR]

Nonpolar [formula] Al0.2Ga0.8N/GaN multiple quantum wells (MQWs) have been grown by molecular beam epitaxy on [formula] Zn0.74Mg0.26O templates on r-plane sapphire substrates. The quantum wells exhibit well-resolved photoluminescence peaks in the ultra-violet region, and no sign of quantum confined Stark effect is observed in the complete multiple quantum well series. The results agree well with flat band quantum well calculations. Furthermore, we show that the MQW structures are strongly polarized along the [0001] direction. The origin of the polarization is discussed in terms of the strain anisotropy dependence of the exciton optical oscillator strengths. [ABSTRACT FROM AUTHOR]

The titanium-doped Ge2Sb2Te5 films were deposited on Si(100) substrates by comagnetron sputtering method. The titanium concentrations in those films were determined by x-ray photoelectron spectroscopy. The influence of Ti doping upon phase change characteristics of the samples has been investigated by x-ray diffraction and a temperature-regulable UVISEL™ typed spectroscopic ellipsometry. With the augmentation of Ti doping concentration, the crystalline temperatures of the films went up while annealing, and the face-centered-cubic phase of them had high thermal stability because of the bond making between Ti and Te elements partly. [ABSTRACT FROM AUTHOR]

A combination of experiments and first-principles method calculations has been applied to investigate the influence of the hydrostatic pressure on the electrical properties of the phase-change material hexagonal Ge2Sb2Te5 (h-GST). Experimentally, it is found that the resistance of h-GST declines monotonically with increasing hydrostatic pressure up to 0.7 GPa. Theoretically, the band-structure calculations revealed that the electronic band gap also decreases with the pressure. The hydrostatic pressure increases the conductivity of h-GST by reducing the electronic band gap. The dEg/dP obtained from theoretical calculations and the d ln ρ/dP by experimental result are in the same order of magnitude. [ABSTRACT FROM AUTHOR]

The effects of the electroforming polarity on the bipolar resistive switching characteristics in SrTiO3-δ thin films have been investigated. The conduction mechanisms of high resistance state and low resistance state are Poole–Frenkel emission and tunneling, respectively. The temperature dependences of the resistance at high and low resistance state are both semiconductorlike. The impact of the polarity of the electroforming voltage on the resistive switching mechanism and the distribution of defects was discussed. A simple model describing the combination of bulk and the interface effect was proposed to explain the resistive switching in this material. [ABSTRACT FROM AUTHOR]

Monte Carlo simulations using a dielectrophoresis model were performed to investigate the microstructural evolution and the conductance change of an Ag30Ge17Se53 electrolyte film clapped by a Ag active electrode, at which a positive bias was applied, and a Pt inert electrode. It has been revealed that driven by the electrical field Ag ions were injected into the electrolyte from the Ag electrode to form conductive particles, thereafter, the particles align themselves in nanowires connecting Ag electrode and Pt electrode and leading to an electrical percolation. It is responsible for the resistive switching of the system. The transmission electron microscopic observations and resistive measurement results are in good agreement with the results of simulations. [ABSTRACT FROM AUTHOR]

The band alignments of (La2O3)0.5(SiO2)0.5(LSO)/GaN and LSO/SiO2/GaN gate dielectric stacks were investigated comparatively by using x-ray photoelectron spectroscopy. The valence band offsets for LSO/GaN stack and LSO/SiO2/GaN stack are 0.88 and 1.69 eV, respectively, while the corresponding conduction band offsets are found to be 1.40 and 1.83 eV, respectively. Measurements of the leakage current density as function of temperature revealed that the LSO/SiO2/GaN stack has much lower leakage current density than that of the LSO/GaN stack, especially at high temperature. It is concluded that the presence of a SiO2 buffer layer increases band offsets and reduces the leakage current density effectively. [ABSTRACT FROM AUTHOR]

Resistive switching devices with a sandwich structure Ag/(AgI)0.5(AgPO3)0.5/Pt were fabricated on silicon(001) wafer by using the pulsed laser deposition method and the focused ion beam nanofabrication technique. (AgI)0.5(AgPO3)0.5 films deposited at room temperature show a nanocrystal structure and the composition of the films was identified by using x-ray photoelectron spectroscopy. The current-voltage characteristics of the Ag/(AgI)0.5(AgPO3)0.5/Pt memory units show good switching behaviors. The ratio of the conductance between the “ON” state (high conductance) and the “off” state (low conductance) reaches 1×106. The ON and OFF states can be effectively written, read, and erased up to 4×105 scanning cycles by using a set of voltage pulses with an amplitude less than 3 V. It also could be observed that the time for the writing and erasing operations could be less than 150 ns. The switching mechanism of the Ag/(AgI)0.5(AgPO3)0.5/Pt memory devices was ascribed to the possible formation and dissolution of Ag filaments in (AgI)0.5(AgPO3)0.5 films induced by the applied electrical pulses with different polarities. [ABSTRACT FROM AUTHOR]

Resistive switching devices with a sandwich structure Ag/(AgI)0.5(AgPO3)0.5/Pt were fabricated on silicon(001) wafer by using the pulsed laser deposition method and the focused ion beam nanofabrication technique. (AgI)0.5(AgPO3)0.5 films deposited at room temperature show a nanocrystal structure and the composition of the films was identified by using x-ray photoelectron spectroscopy. The current-voltage characteristics of the Ag/(AgI)0.5(AgPO3)0.5/Pt memory units show good switching behaviors. The ratio of the conductance between the “ON” state (high conductance) and the “off” state (low conductance) reaches 1×106. The ON and OFF states can be effectively written, read, and erased up to 4×105 scanning cycles by using a set of voltage pulses with an amplitude less than 3 V. It also could be observed that the time for the writing and erasing operations could be less than 150 ns. The switching mechanism of the Ag/(AgI)0.5(AgPO3)0.5/Pt memory devices was ascribed to the possible formation and dissolution of Ag filaments in (AgI)0.5(AgPO3)0.5 films induced by the applied electrical pulses with different polarities. [ABSTRACT FROM AUTHOR]