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Zirconium silicate films with high thermal stability and good electrical properties have been prepared on n-Si(100) substrates and commercially available Pt-coated Si substrates to fabricate metal-insulator-metal (MIM) structures by the pulsed laser deposition (PLD) technique using a Zr0.69Si0.31O2-d ceramic target. Rapid thermal annealing (RTA) in N2 was performed. X-ray diffraction indicated that the films annealed at 800 °C remained amorphous. Differential thermal analysis revealed that amorphous Zr silicate crystallized at 830 °C. X-ray photoelectron spectroscopy showed that RTA annealing of Zr silicate films at 900 °C led to phase separation. The dielectric constant has been determined to be about 18.6 at 1 MHz by measuring the Pt/Zr silicate/Pt MIM structure. The equivalent oxide thicknesses (EOTs) and the leakage-current densities of films with 6-nm physical thickness deposited in O2 and N2 ambient were investigated. An EOT of 1.65 nm and a leakage current of 31.4 mA/cm2 at 1-V gate voltage for the films prepared in N2 and RTA annealed in N2 at 800 °C were obtained. An amorphous Zr-rich Zr silicate film fabricated by PLD looks to be a promising candidate for future high-k gate-dielectric applications. [ABSTRACT FROM AUTHOR]

A memory device has been fabricated using an AgI film sandwiched between a Pt film and an Ag film with the lateral size of the device scaled down to 300?nm. The AgI film was made by the iodination of the Ag film at room temperature and under ambient pressure. The switching between high- and low-resistance states can be realized by applying voltages of different polarities. The switching can be performed under the application of voltage pulses with a 100?Hz frequency for ?103times. The switching times are in the order of microseconds and the retention time is about a week. The switching effects are explained as the electrochemical growth and dissolution of Ag in AgI. [ABSTRACT FROM AUTHOR]

We have proposed a novel memory device with the Cu/CuI0.76S0.14/Pt structure. The intermediate non-stoichiometric film is prepared by pulsed laser deposition. This compound is found with the zincblende structure at room temperature by using x-ray diffraction. Conductance-voltage characteristics reveal that a switching effect exists when the polarity of the voltage biased is changed. By applying a voltage of +0.5?V on the copper electrode, our device is switched on while ?0.8?V induces the OFF-state. The switching operation could be repeated at least 103times, and the GON/GOFFratio is more than 3 × 103. It is expected to be a promising model of nonvolatile memories. With the TEM study, we have analysed the migration of Cu+, S2?and I?under an electric field and attribute the switching effect to the formation and annihilation of ionic conducting paths. [ABSTRACT FROM AUTHOR]

Highly textured perovskite Bi3TiNbO9 (BTN) thin films have been fabricated on fused silica substrates using pulsed laser deposition (PLD). Film surface and structural properties were measured by using atomic force microscopy (AFM) and X-ray diffraction. The optical properties, such as the wavelength dependence of the transmittance and the refractive index, were determined. A band gap of Eg=3.55 eV was obtained experimentally. Optical properties were characterized by using a prism-coupling technique. We observed sharp and distinguishable transverse electric (TE) and transverse magnetic (TM) multimodes and measured the refractive indices of BTN thin films at 632.8 nm. The ordinary and extraordinary refractive indices were calculated to be no=2.3528 and ne=2.3942. This means a birefringence of ?n=ne-no=0.0414 for BTN films. These results show the potential of using BTN films as an electro-optical active material. [ABSTRACT FROM AUTHOR]

A modified design based on the van der Pauw disk to generate a very large geometric magnetoresistance owing to Hall effect is proposed. The conventional disk is a van der pauw disk ( vdp ), in which a concentric circular gold plate is embedded in homogeneous nonmagnetic indium antimonide (S. A. Solin et al., Science 289, 1530 (2000)). Because of the special structures and high mobility of InSb, the vdp -disk exhibits strong Hall effect and shows a magnetoresistance of 100% under a magnetic field of 500 Oe at room temperature. In our modified design, half of the gold circle is replaced with half of a gold ellipse. Higher magnetoresistance in this new design is predicted at room temperature. [ABSTRACT FROM AUTHOR]

Phase transitions of ferroelectromagnetic mode systems are studied by Monte Carlo simulation method. The results show that both magnetoelectric coupling and electrical field can result in a weak ferromagnetic order. Anomalous behaviors of the magnetization and polarization and their susceptibilities near the critical point are observed. A mean-field approach is developed to explain the simulated results, showing a qualitative consistency between them. [ABSTRACT FROM AUTHOR]

Determining the spontaneous polarization is a fundamental problem in the III-nitride field. However the experimental value of the spontaneous polarization has not yet been reported. In this study, a thermodynamic model is proposed to investigate the spontaneous polarization of GaN from the GaN high-pressure phase transition. Total macroscopic polarization is directly expressed as coefficients in expansion, and these coefficients are found to be conducted in experiments. The experimental value of the spontaneous polarization of GaN is estimated to be around -0.022 C/m2. [ABSTRACT FROM AUTHOR]

Single-phased ferroelectromagnet BiFeO[sub 3] ceramics with high resistivity were synthesized by a rapid liquid phase sintering technique. Saturated ferroelectric hysteresis loops were observed at room temperature in the ceramics sintered at 880 °C for 450 s. The spontaneous polarization, remnant polarization, and the coercive field are 8.9 μC/cm[sup 2], 4.0 μC/cm[sup 2], and 39 kV/cm, respectively, under an applied field of 100 kV/cm. It is proposed that the formation of Fe[sup 2+] and an oxygen deficiency leading to the higher leakage can be greatly suppressed by the very high heating rate, short sintering period, and liquid phase sintering technique. The latter was also found effective in increasing the density of the ceramics. The sintering technique developed in this work is expected to be useful in synthesizing other ceramics from multivalent or volatile starting materials. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The interfacial structure and the electrical properties of pulsed laser deposition derived La2O3 ultra-thin films on fully depleted SiGe-on-insulator (FD SGOI) substrates before and after post-annealing in NH3 and N2, respectively, have been investigated comparatively. The results from high-resolution transmission electron microscopy and x-ray photoelectron spectroscopic revealed that interface reactions take place after the NH3 and N2 annealing process, but, as compared with the N2 annealing process, the NH3 annealing process can effectively decrease the thickness of the interfacial layer and incorporate more nitrogen at the dielectric/SiGe interface, resulting in smaller equivalent oxide thickness. The La2O3 capacitors annealed in NH3 show good capacitance-voltage characteristics with negligible hysteresis, smaller interface trap density and lower gate-leakage current density in comparison with those of capacitors annealed in N2. It is demonstrated that the NH3 annealing process can be a promising technology in improving the quality of high-k dielectric on FD SGOI substrates. [ABSTRACT FROM AUTHOR]

RbAg4I5 solid electrolyte films have been prepared using the pulsed laser deposition technique. Their structures have been characterized by x-ray diffraction, and the surface and cross-section morphologies have been investigated by using scanning electron microscopy. It was found that larger energy density of the laser beam favoured the crystallization of RbAg4I5 particles and increased the resistance of the 'off' state, and lower energy density of the laser beam induces the appearance of the AgI phase in the films and reduces the resistance of the 'off' state. A narrow 'window' of the substrate temperature (around 80 °C) for the deposition of pure RbAg4I5 films has also been observed. The RbAg4I5 film deposited on Pt/TiO2/SiO2/Si(1 1 1) substrates at 80 °C shows a uniform and flat surface. All the RbAg4I5 memory devices show obvious resistive switching behaviour. [ABSTRACT FROM AUTHOR]