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The microstructure and chemical bonding states of pure and Ce-doped BiFe[O.sub.3] (BFO) films are characterized by scanning electron microscope (SEM) and Raman spectrum. The enhanced magnetic properties for the [Bi.sub.1-x][Ce.sub.x]Fe[O.sub.3] (BCFO) films are attributed to the presence of [Fe.sup.2+] caused by oxygen vacancies, the suppressed spiral spin structure, and/or the increase canting angle induced by Ce doping.

First-principles methods are used for studying the mechanism of defect formation and electronic structures for 3d transition-metal impurities doped in silicon nanowires. The results have shown that the defect formation energies of Mn and Fe impurities are lower than those of V, Cr, and Co impurities in silicon nanowires.

Sol-gel-derived ([Ba.sub.0.65], [Sr.sub.0.35])Ti[O.sub.3] (BST) films are etched in C[F.sub.4]/Ar and C[F.sub.4]/Ar/[O.sub.2] plasmas by using magnetically enhanced reaction ion etching technology (MERIE) technology. The results have indicated that there are no significant differences between the unetched BST film and the postannealed after etched film with respect to the fitted formulas and average valences of Ti cations.

Abstract  Bi1−x Ce x FeO3 (x = 0, 0.05, 0.1, 0.15 and 0.20) (BCFO) thin films were deposited on Pt/TiN/Si3N4/Si substrates by sol–gel technique. Crystal structures, surface chemical compositions and bonding states of BCFO films were investigated by X-ray diffraction and X-ray photoelectron spectroscopy (XPS), respectively. Compared to BiFeO3 (BFO) counterparts, the fitted XPS narrow-scan spectra of Bi 4f7/2, Bi 4f5/2, Fe 2p3/2, Fe 2p1/2 and O 1s peaks for Bi0.8Ce0.2FeO3 film shift towards higher binding energy regions by amounts of 0.33, 0.29, 0.43, 0.58 and 0.49 eV, respectively. Dielectric constants and loss tangents of the BCFO (x = 0, 0.1 and 0.2) film capacitors are 159, 131, 116, 0.048, 0.041 and 0.035 at 1 MHz, respectively. Bi0.8Ce0.2FeO3 film has a higher remnant polarization (P r = 2.04 μC/cm2) than that of the BFO (P r = 1.08 μC/cm2) at 388 kV/cm. Leakage current density of the Bi0.8Ce0.2FeO3 capacitor is 1.47 × 10−4 A/cm2 at 388 kV/cm, which is about two orders of magnitude lower than that of the BFO counterpart. Furthermore, Ce cations are feasibly substituted for Bi3+ in the Bi0.8Ce0.2FeO3 matrix, possibly resulting in the enhanced ferroelectric properties for the decreased grain sizes and the reduced oxygen vacancies. [ABSTRACT FROM AUTHOR]

The sequential resonant tunneling in La0.5Sr0.5CoO3-δ (LSCO) semiconductor quantum dots (QDs) arrays were observed by current-voltage measurements under room temperature. A series of spikelike current peaks are found, which are resulted from the accumulation and depletion of electrons tunneling through the QDs embedded in insulated barriers. Temperature dependent onset-voltage blueshift and number variation in current peaks are also observed. These results confirm the size-induced metal-to-semiconductor transition in LSCO. [ABSTRACT FROM AUTHOR]