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It has been challenging to achieve combined strong magnetoelectric coupling and narrow ferromagnetic resonance (FMR) linewidth in multiferroic heterostructures. Electric field induced large effective field of 175 Oe and narrow FMR linewidth of 40 Oe were observed in FeCoSiB/Si/SiO2/PMN-PT heterostructures with substrate clamping effect minimized through removing the Si substrate. As a comparison, FeCoSiB/PMN-PT heterostructures with FeCoSiB film directly deposited on PMN-PT showed a comparable voltage induced effective magnetic field but a significantly larger FMR linewidth of 283 Oe. These multiferroic heterostructures exhibiting combined giant magnetoelectric coupling and narrow ferromagnetic resonance linewidth offer great opportunities for integrated voltage tunable RF magnetic devices. [ABSTRACT FROM AUTHOR]

Molecular beam epitaxy deposited rare-earth oxide of Y2O3 has effectively passivated GaSb, leading to low interfacial trap densities of (1-4) x 1012 cm-2 eV-1 across the energy bandgap of GaSb. A high saturation drain current density of 130µA/µm, a peak transconductance of 90 µS/µm, a low subthreshold slope of 147 mV/decade, and a peak field-effect hole mobility of 200 cm² /V-s were obtained in 1 µm-gate-length self-aligned inversion-channel GaSb p-Metal-Oxide-Semiconductor Field-Effect-Transistors (MOSFETs). In this work, high-κ/GaSb interfacial properties were better in samples with a high substrate temperature of 200 °C than in those with high κ'S deposited at room temperature, in terms of the interfacial electrical properties, particularly, the reduction of interfacial trap densities near the conduction band and the MOSFET device performance. [ABSTRACT FROM AUTHOR]

Thick barium hexaferrite [BaO·(Fe2O3)6] films, having the magnetoplumbite structure (i.e., Ba M), were epitaxially grown on c-axis oriented GaN/Al2O3 substrates by pulsed laser deposition followed by liquid phase epitaxy. X-ray diffraction showed (0,0,2n) crystallographic alignment with pole figure analyses confirming epitaxial growth. High resolution transmission electron microscopy images revealed magnetoplumbite unit cells stacked with limited interfacial mixing. Saturation magnetization, 4πMs, was measured for as-grown films to be 4.1±0.3 kG with a perpendicular magnetic anisotropy field of 16±0.3 kOe. Ferromagnetic resonance linewidth, the peak-to-peak power absorption derivative at 53 GHz, was 86 Oe. These properties will prove enabling for the integration of low loss Ba M ferrite microwave passive devices with active semiconductor circuit elements in systems-on-a-wafer architecture. [ABSTRACT FROM AUTHOR]

Employing the focal-series reconstruction technique in high-resolution transmission electron microscopy, we obtained true atomic resolution images of interfacial disorder within cation and anion sublattices across interfaces in an InGaSb/InAs heterostructure. This enabled independent quantitative mapping of changes in the In–Ga and As–Sb contents across interfacial regions ∼0.6 nm in width. A comparison of the cation and anion sublattice images revealed that intermixing at the InGaSb-on-InAs interface is confined to the In–Ga sublattice. Also, atomic scale roughness within the As–Sb sublattice of the InAs-on-InGaSb interface was discerned. This approach is general, permitting atomic-scale compositional analysis of heterointerfaces with two species per sublattice. [ABSTRACT FROM AUTHOR]

Double-crystal x-ray diffraction has been successfully used to study dimensional and compositional variations in Si1-x Gex /Si superlattices. For most samples studied an adequate agreement between theoretical and experimental diffraction profiles is obtained by using a theoretical model (kinematical) which assumes uniform superlattices with abrupt interfaces. In some samples, however, the superlattice-related diffraction peaks reveal an asymmetric broadening which is shown by comparison with dynamical diffraction simulations to be due to a grading in layer compositions and thicknesses throughout the superlattice stack. Detailed analysis of the diffraction data identified a gradual drift of 1.25% in the Ge flux during molecular beam epitaxy (MBE) growth. The MBE system parameters were modified to compensate for this effect and allow the growth of more structurally perfect strained-layer superlattices. [ABSTRACT FROM AUTHOR]

The luminescence properties of undoped semi-insulating liquid encapsulated Czochralski-grown GaAs ingots have been characterized with ∼3-μm spatial resolution using a scanning electron microscope based, cathodoluminescence (CL) system. The use of a cryostat operating at ∼6 K with cooled PbS and Ge detectors for midgap luminescence imaging has revealed for the first time a depletion in the 0.68-eV emission from zones ∼20 μm wide adjacent to individual polygonized dislocation arrays known as cell walls. These midgap luminescence results have been correlated with band edge CL images of cell structures and with dislocation images obtained using double crystal x-ray topography. It is concluded that dislocation arrays attract or getter the defect centers responsible for the 0.68-eV emission in undoped semi-insulating GaAs, as opposed to generating them. [ABSTRACT FROM AUTHOR]

The chemical kinetics of mobile-proton reactions in the SiO[sub 2] film of Si/SiO[sub 2]/Si structures were analyzed as a function of forming-gas anneal parameters in the 300–600 °C temperature range. Our data show that the initial buildup of mobile protons is limited by the rate of lateral hydrogen diffusion into the SiO[sub 2] films. The final density of mobile protons is determined by the cooling rate which terminates the annealing process and, in the case of subsequent anneals, by the temperature of the final anneal. To explain the observations, we propose a dynamical equilibrium model which assumes a reversible interfacial reaction with a temperature-dependent balance. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Adsorption-controlled conditions have been identified and utilized to grow epitaxial bismuth titanate thin films by reactive molecular beam epitaxy. Growth of stoichiometric, phase pure, c-axis oriented, epitaxial films is achieved by supplying a large overabundance of bismuth and ozone continuously to the surface of the depositing film. Titanium is supplied to the film in the form of shuttered bursts each containing a three monolayer dose of titanium to grow one formula unit of Bi[sub 4]Ti[sub 3]O[sub 12]. It is seen from measured film thickness, Rutherford backscattering spectrometry composition measurements, monitoring of reflection high-energy electron diffraction half-order intensity oscillations during growth, and in situ flux measurements using atomic absorption spectroscopy that at suitable temperature and ozone background pressure, the titanium sticking coefficient approaches one and the excess bismuth desorbs from the surface. Film growth proceeds by the formation of mounds whose step heights are predominantly integral multiples of a half-unit cell.© 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]