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Lanthanide doped bismuth titanate films have been shown to exhibit excellent fatigue resistance and higher remanent polarization than SrBi2Ta2O9 films. In this paper we report on the detailed investigation of structural and ferroelectric properties of Nd-doped Bi4Ti3O12 (BNdT) films grown by pulsed laser ablation. Highly epitaxial 300 nm thick (001)-, (118)-, and (104)-oriented BNdT films were deposited on SrRuO3 buffered SrTiO3 substrates of (100), (110), and (111) orientations, respectively. The highest remanent polarization (2Pr) of ∼40 μC/cm2 was observed in the (104)-oriented films at a coercive field of ∼50 kV/cm. Leakage currents of the films were of the order of 10-6-10-5 A/cm2 with (104)-oriented films showing improved behavior. The films showed good fatigue resistance upon bipolar switching up to 109 cycles. [ABSTRACT FROM AUTHOR]

In this paper we discuss the structural modifications observed in a buried amorphous Si (a-Si) layer containing high oxygen concentration level (up to ∼3 at. %) after being implanted at elevated temperature with [sup 16]O[sup +] ions. For implants conducted at temperatures lower than 150 °C, the a-Si layer expands via layer by layer amorphization at the front and back amorphous–crystalline (a–c) interfaces. When performed at temperatures above 150 °C, the implants lead to the narrowing of the buried a-Si layer through ion beam-induced epitaxial crystallization at both a–c interfaces. Cross section transmission electron microscopy analysis of samples implanted at 400 °C revealed an array of microtwins and a dislocation network band in the recrystallized material. In samples implanted at 550 °C, only a buried dislocation network band is observed. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The crystallographic structure of antiphase domain boundaries (APBs) and the magnetic structure of large domains of magnetite (Fe3O4) thin films, which were epitaxially grown on MgO(001) substrates and annealed in an ambient condition, were investigated by scanning tunneling microscopy (STM), transmission electron microscopy (TEM), magnetic force microscopy (MFM), and scanning electron microscopy with polarization analysis (SEMPA). STM and TEM showed the morphology of the APBs in film surfaces and the bulk, whereas MFM and SEMPA showed the magnetic structure of the surfaces. As in previous paper reported by another group, STM and TEM observations revealed the antiphase domains on a scale from tens of nanometers to a few hundred nanometers. Also MFM measurement showed the magnetic domains on a scale of a few hundred nanometers and large-scale undulations of a few micrometers. Our SEMPA observations of the films displayed large-scale magnetic structures on a scale of a few hundred nanometers to a few micrometers. These large-scale magnetic structures are expected to be induced by the enlargement of magnetic domains that contain magnetic moments aligned along a magnetic easy axis. These moments have in-plane components that make the SEMPA images visible. An air-annealing process is needed to change magnetic couplings in APBs and to form large-scale magnetic ordering. [ABSTRACT FROM AUTHOR]

The thermal stability of Er2O3 thin films grown epitaxially on Si substrates has been investigated in this paper by x-ray diffraction and high resolution transmission electron microscopy. The Er2O3/Si(001) films are found to react with Si to form silicates at the temperature of 450 °C in N2 ambience, whereas O2 ambience can prevent the silicate formation even at the temperature of 600 °C. However, at a high temperature of 900 °C in either N2 or O2 ambience, Er2O3 films react with Si, and both silicate and SiO2 are formed in the films. In addition, the Er2O3 films grown on Si(111) substrates show poorer thermal stability than those grown on Si(001) substrates; Er silicide is formed at the interface in the films annealed at 450 °C in O2 ambience, which is attributed to that the reaction product hexagonal ErSi2 is formed more easily on Si(111) than on Si(001) due to structure similarity as well as small lattice mismatch. [ABSTRACT FROM AUTHOR]

In this paper, we use neutron scattering and electrical transport to investigate the paramagnetic to antiferromagnetic phase transition in tetragonal CuMnAs films on GaP(001). X-ray diffraction and cross-sectional transmission electron microscopy measurements show that the films are chemically ordered with high structural quality. The temperature dependence of the structurally forbidden (100) neutron scattering peak is used to determine the Néel temperature, TN. We then demonstrate the presence of a clear peak in the temperature derivative of the resistivity around TN. The effect of disorder-induced broadening on the shape of the peak is discussed. [ABSTRACT FROM AUTHOR]

In this paper, we determine the optical constants and carrier mobilities of Si-doped and Be-doped InAlAs lattice matched to InP. The samples were grown using molecular beam epitaxy and characterized using Hall measurements, variable angle spectroscopic ellipsometry, and room temperature photoluminescence spectroscopy. A Moss-Burstein shift in the fundamental absorption edge was observed in both Si-doped and Be-doped materials. We fitted a multiple-oscillator, critical point model to the dielectric function of the materials extracted using the spectroscopic ellipsometry. The tabulated input parameters of this model allow for accurate calculations of the dielectric function of doped InAlAs to be made, which is useful information for simulating a variety of InP-based optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the influence of strain on anisotropic magnetoresistance (AMR) in La0.67Ca0.33MnO3 (LCMO) films epitaxially grown on BaTiO3(001). For 250-nm-thick LCMO film, the AMR shows a peak near the metal-insulator transition (MIT) temperature, which is similar to that in bulk LCMO. When the thickness of LCMO is decreased to 150 nm, the AMR value achieves a maximum at low temperature. For 80-nm-thick LCMO film, in addition to the appearance of the maximum AMR at low temperature, the symmetry and sign of AMR are also changed, associated with interface strain in the different phases of BaTiO3. In comparison, the AMR for the reference LCMO films grown on SrTiO3(001) shows a maximum value near the MIT temperature regardless of the thickness of film. Our experiment results suggest that not only the strain value but also the distortion type can considerably tune the AMR of LCMO films. [ABSTRACT FROM AUTHOR]

This paper reports on the use of plasma assisted molecular beam epitaxy of AlGaN/GaN-based high electron mobility transistor structures grown on 4 in. Si (111) substrates. In situ measurements of wafer curvature during growth proved to be a very powerful method to analyze the buffer layer's thickness dependent strain. The Ga/N ratio at the beginning of growth of the GaN buffer layer is the critical parameter to control the compressive strain of the entire grown structure. An engineered amount of compressive strain must be designed into the structure to perfectly compensate for the tensile strain caused by differences in the thermal expansion coefficient between the epi-layer and substrate during sample cool down from growth temperatures. A maximum film thickness of 4.2 μm was achieved without the formation of any cracks and a negligible bow of the wafers below 10 μm. Measurement of the as-grown wafers revealed depth profiles of the charge carrier concentration comparable to values achieved on SiC substrates and mobility values of the two dimensional electron gas in the range 1230 to 1350 cm2/Vs at a charge carrier concentration of 6.5-7 1012/cm2. First results on processed wafers with 2 μm thick buffer layer indicate very promising results with a resistance of the buffer, measured on 200 μm long contacts with 15 μm pitch, in the range of R > 109 Ω at 100 V and breakdown voltages up to 550 V. [ABSTRACT FROM AUTHOR]

Solid phase epitaxial regrowth (SPER) is of great technological importance in semiconductor device fabrication. A better understanding and accurately modeling of its behavior are vital to the design of fabrication processes and the improvement of the device performance. In this paper, SPER was modeled by molecular dynamics (MD) with Tersoff potential. Extensive MD simulations were conducted to study the dependence of SPER rate on temperature, growth orientation, pressure, and uniaxial stress. The simulation data were fitted to empirical formula, and the results were compared with experimental data. It was concluded that MD with Tersoff potential can qualitatively describe the SPER process. For a more quantitatively accurate model, larger simulation systems and a better interatomic potential are needed. [ABSTRACT FROM AUTHOR]

Presents an abstract of the paper `Magnetic Measurements on HgMnTe Epitaxial Layers,' presented by A.B. Horsfall, I. Terry, et al, at the American Institute of Physics' 1997 Conference on Magnetism and Magnetic Materials. Measurement of magnetization of epitaxial layers of Hg1-xMnxTe.