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Electrically induced resistive switching (RS) effects have been proposed as the basis for future non-volatile memories. In this work, 9 nm-thick BiFeO3 (BFO) epitaxial thin films were deposited on (001)-oriented SrTiO3 substrates by pulsed laser deposition and their resistive switching (RS) behaviors were investigated. A large resistive switching with ON/OFF ratio of ∼106 is observed, surpassing the performance of most resistive random access memories ever reported. The conducting filament is proposed to dominate the RS behavior in the positive voltage region, while the modulation of ferroelectric polarization is suggested to play a significant role in the negative voltage region. Our study significantly deepens the understanding of the physical origin of RS and could provide a reference for designing high-performance memories and memristors based on ultrathin ferroelectric films. [ABSTRACT FROM AUTHOR]

BiInO3 is a potentially polar oxide with distinct optical properties whose origin could result from a surface that has not been well characterized. The surface properties of BiInO3 thin films have been characterized here by temperature dependent angle-resolved x-ray photoemission spectroscopy. A large surface to bulk core-level binding energy shift for the In 3d5/2 core-level is identified, indicating a surface very different from the bulk. BiInO3 terminates in indium oxide and loses bismuth from the surface of the film at T = 573 K. The Debye–Waller plots suggest effective Debye temperatures of 263 ± 10 and 556 ± 27 K for the surface and bulk components of In 3d core-level, respectively. [ABSTRACT FROM AUTHOR]

10.1063/5.0044758 82 M. Makarovic, M. Ç. Bayir, H. Ursic, A. Bradesko, and T. Rojac, "Domain wall conductivity as the origin of enhanced domain wall dynamics in polycrystalline BiFeO3", J. Appl. Phys. 10.1063/5.0029582 79 D. Zhang, D. Sando, Y. Pan, P. Sharma, and J. Seidel, "Robust ferroelectric polarization retention in harsh environments through engineered domain wall pinning", J. Appl. Phys. Today, it is established that ferroic domain walls represent outstanding functional nano-entities with unique physical properties, which are exploited in the rapidly expanding field of domain-wall nanoelectronics.[[16], [23]] Due to their low local symmetry and the distinct structural, electric, or magnetic environment, ferroic domain walls can behave substantially differently than the surrounding domains. Ferroic materials exhibit long-range order with respect to their elastic, electric, or magnetic properties, giving rise to fascinating physics and functional properties that are used in, e.g., state-of-the-art sensor technology, energy harvesting, and medical diagnosis. [Extracted from the article]

First-principles calculations within the local density approximation were carried out to explain the ground state and electronic properties of a vacuum/ PbTiO 3 / SrTiO 3 / PbTiO 3 / SrRuO 3 multilayer in a monodomain phase. Open-circuit boundary conditions were assumed, considering the electric displacement field, D , as the fundamental electrical variable. The direction and the magnitude of D can be monitored by proper treatment of the PbO surface layer, introducing external fractional charges Q in the surface atomic layers by means of virtual crystal approximation. Different excess or deficit surface charges (from Q = ± 0.05 to Q = ± 0.15) were considered, corresponding to small values of the polarization (up to ± 0.16 C / m 2) in both directions. The layer-by-layer electric polarization, tetragonality, and the profile of the electrostatic potential were computed, as well as the projected density of states, as a function of electric displacement field. The magnitude of D is preserved across the dielectric layers, which translates into a polarization of the SrTiO 3 spacer layer. The tetragonality of the two PbTiO 3 layers is different, in good agreement with experimental x-ray diffraction techniques, with the layer closer to the free surface exhibiting a smaller value. This is attributed to the interplay with surface effects that tend to contract the material in order to make the remaining bonds stronger. Our calculations show how the final structure in this complex oxide heterostructure comes from a delicate balance between electrical, mechanical, and chemical boundary conditions. [ABSTRACT FROM AUTHOR]

High-resolution piezoresponse force microscopy is used to investigate the nanoscale kinetics of ferroelectric domain wall motion in polycrystalline ferroelectric thin films. The kinetic model has predicted the wall velocity to go through changing maxima as a function of time during polarization relaxation process.

CuCr1-xMgx02 wide band gap semiconductor films and powders were studied to determine p-type conductivity.

Epitaxial ferroelectric films undergoing a cubic-tetragonal phase transformation relax internal stresses due to the structural phase transformation and the difference in the thermal expansion coefficients of the film and the substrate by forming polydomain structures. Experimental evidence on the formation of the three-domain structure based on transmission electron microscopy in ferroelectric films is presented.

A study investigated the effect of film thickness on structural and electrical properties of epitaxial lead zirconate titanate films that were prepared by pulsed laser ablation and characterized by four-circle X-ray diffraction, pulsed switching measurements and transmission electron microscopy. The study demonstrated a strong dependence of the domain structure of the film on the thickness of the ferroelectric layer.

A study was conducted on epitaxial ferroelectric thin films in connection with their potential applications as elements of non-volatile random access memories and static ferroelectric random access memories, optical waveguides and pyroelectric detectors. The experiment focused on the effect of La0.5Sr0.5CoO3 electrode layer thickness and configuration on the microstructure of PbZr0.2Ti0.8O3 films on SrTiO3 substrates in conjunction with previous theoretical investigations.

Surfaces patterned with quasi-periodic array of sub-wavelength air holes have been studied for their effectiveness in suppressing air-substrate reflection in the wavelength range of 450-1350 nm. Superlattice structures formed by superposing two different quasiperiodic arrays with 450 nm deep holes showed reflectance of ~2% (compared to 6% for unpatterned substrate) for all measured incidence angles up to 50_ and also show very weak polarization dependence. Dense k-space of quasiperiodic array along with the graded index offered by tapered holes provide broadband, polarization independent, and omnidirectional antireflection property. [ABSTRACT FROM AUTHOR]

Solid state dewetting and the subsequent morphological changes for platinum thin films grown on zinc oxide (ZnO) buffered (001) silicon substrates (Pt/ZnO/SiO2/(001)Si system) is investigated under vacuum conditions via a custom-designed confocal laser microscope coupled with a laser heating system. Live imaging of thin film dewetting under a range of heating and quenching vacuum ambients reveals events including hillock formation, hole formation, and hole growth that lead to formation of a network of Pt ligaments, break up of Pt ligaments to individual islands and subsequent Pt islands shape reformation, in chronological fashion. These findings are corroborated by ex-situ materials characterization and quantitative electron microscopy analysis. A secondary hole formation via blistering before film rupture is revealed to be the critical stage, after which a rapid dewetting catastrophe occurs. This process is instantaneous and cannot be captured by ex-situ methods. Finally, an intermetallic phase forms at 900 °C and alters the morphology of Pt islands, suggesting a practical limit to the thermal environments that may be used for these platinized silicon wafers in vacuum conditions. [ABSTRACT FROM AUTHOR]

Domain nucleation in epitaxial (001)-oriented Pb(Zr0.2TiO0.8)O3 ultrathin ferroelectric films under a sub-critical field regime is investigated by means of piezoresponse force microscopy (PFM). Analytical fits to the domain radius and velocity as a function of time indicate that 180 domain nucleation and growth under a biased PFM tip exhibit a thermally activated, creep behavior. It is also found that an electric field of less than half of the local coercive (or critical) field Ecloc detected by PFM can create stable domains under prolonged bias application. Under these sub-critical bias conditions, it is the temporal evolution of the local electric-field profile due to the slow drift of screening charges or defects (e.g., ionic vacancies) that dictates domain nucleation and growth. [ABSTRACT FROM AUTHOR]

Phase pure bismuth ferrite (BiFeO3) thin films with (001)-oriented epitaxial structure are realized on lanthanum strontium manganite (La0.67Sr0.33MnO3) buffered (001)-SrTiO3 substrates by chemical solution deposition. The annealing process is optimized such that a stoichiometric precursor can be used to accurately control the Bi:Fe ratio. Ferroelectric, dielectric, and resistive switching behaviours are investigated for 40 nm, 70 nm, and 150 nm BFO thin films. While the thinnest film (40 nm) shows very leaky loops, square and fully saturated polarization hysteresis loops are shown for the thicker films. The highest remanent polarization (2Pr=100 μC/cm²) and relative dielectric constant (ϵr=613) are obtained in the 150 nm BFO thin film. High cycle fatigue tests show that the thick films are resistant to polarization fatigue. Piezoresponse force microscopy results show that the domain structure varies with thickness. Resistive switching and polarization mediated diode effects are also observed. These robust properties suggest that chemical solution deposition derived BiFeO3 thin films can offer a viable low cost alternative. [ABSTRACT FROM AUTHOR]

Domain microstructures in single crystal lamellae of 88%Pb(Zn1/3Nb2/3)O3-12%PbTiO3 (cut from bulk using focused ion beam milling) have been mapped using both piezoresponse force microscopy and transmission electron microscopy. Dramatic changes from mottled microstructures typical of relaxors to larger scale domains typical of ferroelectrics have been noted. Stresses associated with substrate clamping are suspected as the cause for the transition from short- to long-range polar order, akin to effects induced by cation ordering achieved by thermal quenching. [ABSTRACT FROM AUTHOR]

Domain microstructures in single crystal lamellae of 88%Pb(Zn1/3Nb2/3)O3-12%PbTiO3 (cut from bulk using focused ion beam milling) have been mapped using both piezoresponse force microscopy and transmission electron microscopy. Dramatic changes from mottled microstructures typical of relaxors to larger scale domains typical of ferroelectrics have been noted. Stresses associated with substrate clamping are suspected as the cause for the transition from short- to long-range polar order, akin to effects induced by cation ordering achieved by thermal quenching. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including the use of piezoresponse force microscopy (PFM) to prove electromechanically active materials' functional properties, epitaxial multiferroics composites, and robust properties of sol-gel.

Cation intermixing at functional oxide interfaces remains a highly controversial area directly relevant to interface-driven nanoelectronic device properties. Here, we systematically explore the cation intermixing in epitaxial (001) oriented multiferroic bismuth ferrite (BFO) grown on a (001) lanthanum aluminate (LAO) substrate. Aberration corrected dedicated scanning transmission electron microscopy and electron energy loss spectroscopy reveal that the interface is not chemically sharp, but with an intermixing of ~2 nm. The driving force for this process is identified as misfit-driven elastic strain. Landau-Ginzburg-Devonshire-based phenomenological theory was combined with the Sheldon and Shenoy formula in order to understand the influence of boundary conditions and depolarizing fields arising from misfit strain between the LAO substrate and BFO film. The theory predicts the presence of a strong potential gradient at the interface, which decays on moving into the bulk of the film. This potential gradient is significant enough to drive the cation migration across the interface, thereby mitigating the misfit strain. Our results offer new insights on how chemical roughening at oxide interfaces can be effective in stabilizing the structural integrity of the interface without the need for misfit dislocations. These findings offer a general formalism for understanding cation intermixing at highly strained oxide interfaces that are used in nanoelectronic devices. [ABSTRACT FROM AUTHOR]

Trilayer heterostructures consisting of a ferroelectric bismuth ferrite (BFO) film sandwiched between ferromagnetic lanthanum strontium manganese oxide (LSMO) films were fabricated using pulsed laser deposition. Both BFO thicknesses (20 nm, 5 nm) and cooling rates were varied to investigate the role of processing parameters on the chemistry of the interfaces. The interfaces were investigated using a dedicated aberration corrected scanning transmission electron microscope (STEM) operated at 100 kV via STEM-high angle annular dark field (STEM-HAADF) and STEM-electron energy loss spectroscopy (STEM-EELS) modes. Combined analysis through STEM-HAADF and STEM-EELS revealed the formation of lattice distortion in certain regions of the BFO layer for the ∼5 nm film. Piezoresponse force microscopy (PFM) studies of the ∼5 nm BFO sample revealed weak ferroelectric domain switching. Stacking fault defects with mixed valence manganese (Mn-B site cation) were formed in the top LSMO layer when the heterostructure was cooled at a slower rate irrespective of BFO thickness, thereby demonstrating the effect of processing kinetics on the physical integrity of the heterostructure. [ABSTRACT FROM AUTHOR]

This report investigates the phase evolution pathway of magnetite nanocrystal synthesis on oxide-supported substrates. A template-free phase separation approach, which exploits the thermodynamic instability of ternary perovskite BiFeO3 and inherent volatility of bismuth oxide in low oxygen pressure and high temperature is presented. The formation of an intermediate hematite nanocrystal phase is found as a key step that controls the eventual size and morphology of the magnetite nanocrystals. X-ray absorption spectra measurements and X-ray magnetic circular dichroism confirm that the spectral fingerprints of the magnetite nanocrystals match with that of bulk crystals. Magnetic measurements show that magnetic anisotropy is directly attributed to the nanocrystal morphology. [ABSTRACT FROM AUTHOR]

This paper examines the structural properties of gallium phosphide layers by high resolution x-ray diffraction and atomic force microscopy measurements. GaP layers are grown on misoriented and nominally exactly oriented silicon (001) substrates by metalorganic vapor phase epitaxy. Structural characterization is performed by reciprocal lattice map and transverse scan measurements of (00l)-reflections (l = 2, 4, 6). Transverse scan line profiles of GaP layers on exactly oriented and misoriented substrates are compared thoroughly and antiphase disorder related satellite peaks are observed on exactly oriented substrates. In addition, results imply that antiphase disorder is self-annihilated on misoriented substrates. The dependence of crystallographic tilt on growth temperature indicates structural coherence. Williamson-Hall-like plot of transverse scans reveals the lateral correlation length of crystalline defects of 79 nm which gives the average size of the mosaic crystallites. In addition, the mosaicity of the GaP layer is 0.042°. [ABSTRACT FROM AUTHOR]

Detailed structural investigations on the substitution-induced structural phase transition from the rhombohedral phase to an orthorhombic phase in (Bi,RE)FeO3 epitaxial thin films (RE = La, Sm, and Dy) grown on (100) SrTiO3 substrates are presented. X ray diffraction reveals that the unit cell dimensions of the orthorhombic phase are strongly dependent on the type of the RE dopant. For RE = La3+ ion, which has an ionic size comparable to the Bi3+ ion, the unit cell is found to be a0 × a0 × 2a0, where a0 is the pseudo-cubic lattice parameter. This is in contrast with the [Square_Root]2a0 × [Square_Root]2a0 × 2a0 unit cell for the case of smaller ionic radius RE (= Sm and Dy) elements. While clear double-hysteresis loops in the polarization versus electric-field curves due to field-induced transitions are observed for smaller ionic radius RE (= Sm and Dy), no signature of the double hysteresis loops is observed for the RE = La case across the structural boundary. We have also performed systematic tracking of the structural phases as functions of the RE composition and temperature, based on which we propose a phase diagram. This work reveals that the ionic size of the RE element plays a critical role in the evolution of the structural and functional properties of RE-substituted BiFeO3 thin film materials systems. [ABSTRACT FROM AUTHOR]

We investigate the interfacial structure of PbZr0.20Ti0.80O3 (PZT)/La0.67Sr0.33MnO3 (LSMO)/SrTiO3 heterostructures by combining low-magnification transmission electron microscopy imaging and spectroscopy techniques with high-resolution spherical-aberration corrected scanning transmission electron microscopy imaging, geometrical phase analysis, and spectroscopy results. For certain thickness regimes, the interface between PZT and LSMO is found to have a significant density of planar defects at the interface. Both A-site cation (Pb) diffusivity and highly inhomogeneous local strains are observed at the boundaries of the defect areas. It is proposed that Pb is incorporated as PbO Ruddlesden-Popper planar fault within the LSMO. These results underline the importance of chemical fluctuations caused by long-range strain fields associated with defect cores. [ABSTRACT FROM AUTHOR]

We report a study on multiferroic bismuth ferrite (BiFeO3, BFO)-ferromagnetic lanthanum strontium manganese oxide (La0.7Sr0.3MnO3, LSMO) epitaxial interfaces by scanning transmission electron microscopy-energy dispersive spectroscopy (STEM-EDS) and energy-filtered transmission electron microscopy (EFTEM). Epitaxial (001) oriented LSMO/BFO heterostructures were fabricated on a (001) strontium titanate (SrTiO3, STO) substrate using pulsed laser deposition (PLD). Different cooling conditions to room temperature (rapid or slow) were used to investigate the effect of fabrication conditions on the structural quality of the interfaces. The combined analysis of bright field transmission electron microscopy imaging, STEM-EDS and EFTEM data reveals that the LSMO-BFO heterostructure interface is free from any defects but the phases are chemically interdiffused over a length scale of ∼4 nm. [ABSTRACT FROM AUTHOR]

We develop a nonlinear thermodynamic model to predict the phase stability of ultrathin epitaxial (001)-oriented ferroelectric PbZr1-xTixO3 (PZT) films with x=1.0, 0.9, 0.8, and 0.7 on substrates which induce anisotropic in-plane strains. The theoretical formalism incorporates the relaxation by misfit dislocations at the film deposition temperature, the possibility of formation of ferroelectric polydomain structures, and the effect of the internal electric field that is generated due to incomplete charge screening at the film-electrode interfaces and the termination of the ferroelectric layer. This analysis allows the development of misfit strain phase diagrams that provide the regions of stability of monodomain and polydomain structures at a given temperature, film thickness, and composition. It is shown that the range of stability for rotational monodomain phase is markedly increased in comparison to the same ferroelectric films on isotropic substrates. Furthermore, the model finds a strong similarity between ultrathin PbTiO3 and relatively thicker PZT films in terms of phase stability. The combinations of the in-plane misfit strains that yield a phase transition sequence that results in a polarization rotation from the c-phase (polarization parallel to the [001] direction in the film) to the r-phase, and eventually to an in-plane polarization parallel to the [110] direction (the aa-phase) is determined to be the path with the most attractive dielectric and piezoelectric coefficients resulting in enhancements of 10 to 100 times in the dielectric permittivity and piezoresponse compared to bulk tetragonal ferroelectrics of the same PZT composition. [ABSTRACT FROM AUTHOR]

Electromigration (EM) is an important failure mechanism in integrated circuit interconnections. Various models have been proposed to study the interconnect degradation due to EM from different perspectives. As the interconnect linewidth shrinks to submicrometer and below, a small growth in void size after void nucleation can sever the conduction path, and hence void nucleation time becomes the dominant part of the time to failure of an interconnect and the primary damage mechanism in EM failure. In this work, an alternative concept of EM modeling is proposed, and the EM lifetime of an interconnect during void nucleation is derived theoretically. A physics-based predictive Monte Carlo simulation methodology is used to model the void nucleation process during EM. To demonstrate the modeling concept and the simulation methodology developed in the present study, Al interconnect test structure is chosen as an illustration and it is shown that the model can predict the voiding location in the interconnect and estimate the median time to failure as verified experimentally. [ABSTRACT FROM AUTHOR]

We investigate theoretically ferroelastic domain fractions in a heteroepitaxial bilayer consisting of (001) tetragonal PbZrxTi1-xO3 and (001) rhombohedral PbZr1-xTixO3 on a thick (001) passive substrate as a function of the lattice misfit strain between layers and the substrate. By considering the self-strain in each layer and the indirect elastic interaction between the layers, we provide a numerical analysis of the relative domain fractions in the tetragonal layer of a (001)PbZr0.2Ti0.8O3/(001)PbZr0.8Ti0.2O3 and (001)PbZr0.4Ti0.6O3/(001)PbZr0.6Ti0.4O3 bilayer structure as a function of the tetragonal layer thickness on (001)LaAlO3, (001)SrTiO3, and (001) MgO. It is found that the elastic coupling between the tetragonal and rhombohedral layers leads to an excess elastic energy in the tetragonal layer, resulting in a two to three times increase in the ferroelastic domain volume fraction of the tetragonal layer compared to single-layer films of similar thickness. These results show alternate ways of engineering ferroelastic domain structures in ferroelectric thin films. [ABSTRACT FROM AUTHOR]

Traditionally, the lognormal distribution has been used to analyze electromigration (EM) failure data for both Al- and Cu-based interconnect technologies. However, from a statistical perspective, the lognormal distribution is found to be inappropriate for submicron interconnects because their resistance degradation profiles are no longer “gradual” as compared to the wider interconnects. In such cases, the gamma distribution is found to be a good choice to represent such failures which are initially “gradual” and later “catastrophic” in nature. The invalidity of the lognormal model for submicron interconnects is assessed and a statistical proof in favor of the gamma statistics is presented. Experimental EM test data for submicron Cu interconnects are analyzed and it is found that the data fitting is generally more accurate for submicron interconnects when the gamma distribution is used. The use of a gamma distribution also changes the field operation lifetime estimates obtained through reliability extrapolation. [ABSTRACT FROM AUTHOR]

We present a theoretical analysis of the scaling of the polarization and the static dielectric susceptibility through a mean-polarization approach for ultrathin epitaxial PbZrxTi1-xO3 thin films. We use the traditional Euler-Lagrangian framework applied to a Landau-Ginzburg-Devonshire (LGD) nonlinear thermodynamic treatment. The novelty of our approach is that the model hinges on using experimentally measured correlation lengths and temperature scaling relationships to give the size-dependent expansion parameters of the nonlinear thermodynamic potential. These are then used in a Taylor series expansion of the polarization at the center of the film. We show that this method is able to correctly predict experimentally observed scaling without the need for the so-called extrapolation length (which is impossible to measure experimentally). Furthermore, as no implicit correlation between the correlation length (ξ) and the coefficient of the gradient term in the LGD potential (g11) is assumed, the model thus involves fully experimentally measurable parameters and their systematic temperature dependence rather than implicit assumptions. The model finds that the Curie temperature in ultrathin films is more sensitive to epitaxial strain as compared to the polarization and that the critical thickness is strongly dependent on the “temperature-epitaxial strain” parameter space. Interestingly, while it finds that at lower temperatures the depolarization field does play a strong role in the thickness dependence as well as spatial profile of the polarization, with increasing temperature, a significant weakening of the role of depolarization fields occurs. Consequently the interface-induced suppression is lower and, as a result, the polarization profile is more homogenous at higher temperatures. This indicates that systematic temperature dependent studies are fundamental to further understanding of size effects in ferroelectrics. [ABSTRACT FROM AUTHOR]

Scaling of the structural order parameter, polarization, and electrical properties was investigated in model ultrathin epitaxial SrRuO3/PbZr0.2Ti0.8O3/SrRuO3/SrTiO3 heterostructures. High-resolution transmission electron microscopy images revealed the interfaces to be sharp and fully coherent. Synchrotron x-ray studies show that a high tetragonality (c/a∼1.058) is maintained down to 50 Å thick films, suggesting indirectly that ferroelectricity is fully preserved at such small thicknesses. However, measurement of the switchable polarization (ΔP) using a pulsed probe setup and the out-of-plane piezoelectric response (d33) revealed a systematic drop from ∼140 μC/cm2 and 60 pm/V for a 150 Å thick film to 11 μC/cm2 and 7 pm/V for a 50 Å thick film. This apparent contradiction between the structural measurements and the measured switchable polarization is explained by an increasing presence of a strong depolarization field, which creates a pinned 180° polydomain state for the thinnest films. Existence of a polydomain state is demonstrated by piezoresponse force microscopy images of the ultrathin films. These results suggest that the limit for a ferroelectric memory device may be much larger than the fundamental limit for ferroelectricity. [ABSTRACT FROM AUTHOR]

Landau–Devonshire-type phenomenological thermodynamic theory is employed to explain the electric field dependence of piezoelectric properties of tetragonal single domain PbZr[sub x]Ti[sub 1-x]O[sub 3] (PZT). The strong nonlinearity of the converse piezoelectric coefficient under a large external electric field is proved to be intrinsic both in bulk crystal and epitaxial tetragonal PZT thin films. The tunability of piezoelectric responses by an external electric field and its dependence on the film/substrate misfit and elastic compliance of thin films are characterized quantitatively. The theoretical predictions are in good agreement with the experimental results of piezoresponse scanning microscopy. Due to the large tunability of piezoresponse in it, PZT 50/50 (x=0.5) epitaxial film is a promising candidate for use in future tunable devices. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have performed depth profile studies of the structure of PbZr[sub 0.2]Ti[sub 0.8]O[sub 3] films of different thicknesses deposited on SrTiO[sub 3] substrates prepared by pulsed laser deposition, using grazing incident x-ray scattering (GIXS). The in-plane structure of the films reveals these consist of up to three domains, one c-axis domain, and two a-axis domains, denoted al and a2. GIXS measurements show the evolution of in-plane compression of the lattice parameter as a function of depth within the films, particularly in the a1 domains. This strain evolution is accompanied by the presence of twist grain boundaries in the plane in some films. The measured in-plane lattice parameters are asymmetric, which suggests an orthorhombic distortion of the lattice in the plane of the films. [ABSTRACT FROM AUTHOR]

Voltage-modulated scanning force microscopy (Piezoresponse microscopy) is applied to investigate the domain structure in epitaxial PbZr[sub 0.2]Ti[sub 0.8]O[sub 3] ferroelectric thin films grown on (001) SrTiO[sub 3]. By monitoring the vertical and lateral differential signals from the photodetector of the atomic force microscope it is possible to separate out and observe the out-of-plane and in-plane polarization vectors in the thin film individually. The relative orientation of the polarization vectors across a 90° domain wall is observed. Nucleation of new reversed 180° domains at the 90° domain wall is studied and its impact on the rotation of polarization within the a domain is analyzed as a function of reversal time. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

CuCr[sub 1-x]Mg[sub x]O[sub 2], a wide band gap semiconductor with the delafossite structure, has been synthesized in bulk and thin-film form. Bulk undoped CuCrO[sub 2] is almost black and has moderate conductivity with p-type carriers. Upon doping with 5% Mg, the conductivity increases by a factor of 1000. In films, the best p-type conductivity is 220 S cm[sup -1] in CuCr[sub 0.95]Mg[sub 0.05]O[sub 2], a factor of 7 higher than previously reported for Cu-based p-type delafossites. Undoped films have a conductivity of order 1 S cm[sup -1]. Films are usually polycrystalline on amorphous substrates, but undoped films can be c-axis oriented if deposited at or above 650 °C. Optical and ultraviolet transmission data indicate a direct band gap of 3.1 eV. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Gd2Ni3Si5 and Sm2Ni3Si5 crystallizing in orthorhombic U2Co3Si5-type structures, similar to rare earth species, have similar antiferromagnetic ordering with different de Gannes scale ordering temperature. Magnetic susceptibility of Gd2Ni3Si5 shows a Curie-Weiss pattern and that of Sm2Ni3Si5 shows a deviated Curie-Weiss pattern due to the low excited state of Sm3+ ions.

Electromigration (EM) is a very failure mechanism in integrated circuit interconnections and various models are proposed to analyze the interconnect degradation due to EM from different perspectives. Al interconnect test structure is chosen as an illustration and the model has predicted the voiding location in interconnect and has estimated the median time to failure.

The scaling of the polarization and the static dielectric susceptibility is by using a mean-polarization approach for ultrathin epitaxial Pb[Zr.sub.x][Ti.sub.1-x][O.sub.3] thin films. The Curie temperature in ultrathin films is more sensitive to epitaxial strain when compared to the polarization and the critical thickness is dependent on the temperature-epitaxial strain parameter space.

The gamma distribution is better than the lognormal distribution method for analyzing electromigration (EM) failure data for both Al- and Cu-based interconnect technologies. The use of gamma distribution has also changed the field operation lifetime estimates that are obtained from reliability extrapolation.

Magnetic and transport properties of a series of compounds R2Coln8 are investigated. The Pr compounds does not show magnetic ordering but exhibits a magnetic susceptibility at low temperatures reminiscent crystalline electric field effects.

The magnetization and (super 151)Eu Mossbauer studies in ordered perovskite-type oxides, Ba2EuRu1-xCu(sub x)O6 (x=0.0, 0.1 and 0.2), are reported. Both the magnetization and Mossbauer measurements indicate that the magnetic ordering temperature is unchanged as Cu partially substitutes Ru.

A Raman spectroscopy is used to measure the dependence of B12As2 phonon modes in hydrostatic pressure up to 15 GPa. It is reported that different pressure co-efficient exist for the Eg modes.

Focuses on a study which discussed the effect of the electrode layer on the polydomain structure of epitaxial lead zirconium titanium oxide thin films. Microstructural characterization of the study; Theoretical interpretation of the study; Conclusion.

The structure of PbZr(sub 0.2)Ti(sub 0.8)O(sub 3) films of different thickness deposited on SrTiO(sub 3) substrates prepared by pulsed laser deposition, is studied by using grazing incident x-ray scattering (GIXS) technique. GIXS measurements show the evolution of in-plane compression of the lattice parameter as a function of depth within the films.