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We report different growth modes and corresponding magnetic properties of thin EuSe films grown by molecular beam epitaxy on BaF2, Pb1−xEuxSe, GaAs, and Bi2Se3 substrates. We show that EuSe grows predominantly in the (001) orientation on GaAs(111) and Bi2Se3, but along the (111) crystallographic direction on BaF2 (111) and Pb1−xEuxSe (111). High resolution transmission electron microscopy measurements reveal a sharp and highly crystalline interface for both (001) and (111) EuSe films. In agreement with previous studies, ordered magnetic phases include antiferromagnetic, ferrimagnetic, and ferromagnetic phases. In contrast to previous studies, we found a strong hysteresis of the antiferromagnetic–ferrimagnetic transition. The ability to grow epitaxial films of EuSe on Bi2Se3 and of Bi2Se3 on EuSe enables further investigation of interfacial exchange interactions between various phases of an insulating metamagnetic material and a topological insulator. [ABSTRACT FROM AUTHOR]

We investigate the magneto-optical (MO) polar Kerr enhancement of Fabry–Pérot cavities with perpendicular magnetic anisotropy for chemical and biological sensing applications. The MO cavities consist of stacked films with a half-mirrored surface layer, a dielectric interference layer, a total-reflection mirror, and a magnetic metal layer. Co80Pt20 and Al-doped ZnO (AZO) thin films were utilized as the magnetic and interference layers, respectively. The cavities produce two types of MO enhancement depending on the thickness of the magnetic layer. The sample with a thick magnetic layer as a total-reflection mirror generates a single peak in the polar Kerr spectrum. Contrarily, inserting a several-nanometer-thick CoPt layer into the AZO layer produces a resonant-type spectrum. Although both samples generate large MO enhancement factors (>50), the magnetic properties significantly differ. The AZO/CoPt/AZO interference layer controls the crystalline and interface conditions and produces a square-shaped out-of-plane hysteresis loop with a large Kerr rotation angle. Moreover, the use of an ultrathin CoPt film significantly reduces the saturation magnetization field. Thus, Fabry–Pérot cavities with a CoPt/AZO interference layer may serve as high-sensitivity, low-energy-consumption sensor elements. [ABSTRACT FROM AUTHOR]

We investigate how varying molecular topology of polymers influences crystallization in thin polymer films. In particular, we simulate linear and star polymers of fixed mass having a progressively increasing number of arms (f ≤ 16) in a system where the linear polymer exhibits crystallization in a thin film geometry, but no apparent crystallization in the corresponding bulk material. The degree of crystallization of the polymer film at long times decreases progressively with increasing f, and no crystallization is observed beyond f = 8. Crystallization for smaller values of f develops as a sigmoidally shaped wavefront initiating from the supporting crystalline interface. We suggest that large shape fluctuations and the competition of length scales of star polymers with high f lead to inhibited crystallization. [ABSTRACT FROM AUTHOR]

A variational model to simultaneously treat Stress-Driven Rearrangement Instabilities, such as boundary discontinuities, internal cracks, external filaments, edge delamination, wetting, and brittle fractures, is introduced. The model is characterized by an energy displaying both elastic and surface terms, and allows for a unified treatment of a wide range of settings, from epitaxially-strained thin films to crystalline cavities, and from capillarity problems to fracture models. The existence of minimizing configurations is established by adopting the direct method of the Calculus of Variations. The compactness of energy-equibounded sequences and energy lower semicontinuity are shown with respect to a proper selected topology in a class of admissible configurations that extends the classes previously considered in the literature. In particular, graph-like constraints previously considered for the setting of thin films and crystalline cavities are substituted by the more general assumption that the free crystalline interface is the boundary, consisting of an at most fixed finite number m of connected components, of sets of finite perimeter. Finally, it is shown that, as m → ∞ , the energy of minimal admissible configurations tends to the minimum energy in the general class of configurations without the bound on the number of connected components for the free interface. [ABSTRACT FROM AUTHOR]

Abstract Bismuth magnesium niobate (Bi 3/2 MgNb 3/2 O 7 , BMN) thin films were prepared on bare SiO 2 /HR-Si and Pt/TiO 2 /SiO 2 /HR-Si substrates by using sol-gel spin coating technique followed by rapid thermal annealing process. The influence of the interface on crystalline structure and tunable dielectric properties of the two types of BMN films were investigated. It was found that the BMN films prepared on SiO 2 /Si substrate with a BMN/SiO 2 interface structure had higher orientation and better crystallinity. The deposited BMN thin films with a BMN/SiO 2 interface structure exhibited superior tunability of 52.5%, while it showed a relative small tunability value of the film with BMN/Pt interface structure. It suggests that the interface state between the films and substrates, electric field distribution, and orientation degree are responsible for the impacts on the microstructure and tunable dielectric properties of the BMN thin films. [ABSTRACT FROM AUTHOR]

Deals with the preparation of Pb(Zr,Ti)O3 (PZT) thin films by sol gel processing. Investigation on the crystalline phases of thin films; Properties of PZT thin films; Discussion on electro-optic effects in PZT thin films prepared by chemical methods.

Analyzing the orientation of polymeric crystalline lamella at the surface of thin films can be challenging. Even though atomic force microscopy (AFM) is often sufficient for this analysis, there are cases when imaging is not sufficient to confidently determine lamellar orientation. Here, we used sum frequency generation (SFG) spectroscopy to analyze the lamellar orientation at the surface of semi-crystalline isotactic polystyrene (iPS) thin films. The SFG orientation analysis indicated that the iPS chains are oriented perpendicular to the substrate (flat-on lamellar orientation), which was confirmed by AFM. By analyzing the evolution of the SFG spectral features with the progress of crystallization, we demonstrated that the ratios of the SFG intensities of the phenyl ring resonances are a good indication of the surface crystallinity. Furthermore, we explored the challenges associated with SFG measurements of heterogeneous surfaces, which is commonly present in many semi-crystalline polymeric films. To the best of our knowledge, this is the first time that the surface lamellar orientation of semi-crystalline polymeric thin films was determined by SFG. Also, this work pioneers in reporting the surface conformation of semi-crystalline and amorphous iPS thin films by SFG and in linking the SFG intensity ratios to the progress of the crystallization and the surface crystallinity. This study demonstrates the potential applicability of SFG spectroscopy in the conformational analysis of polymeric crystalline structures at interfaces and opens the way to the investigation of more complex polymeric structures and crystalline arrangements, especially for the case of buried interfaces, where AFM imaging is not an option. [Display omitted] • Surface lamellar orientation of polymer thin films determined by SFG. • Surface of semi-crystalline iPS thin films is dominated by flat-on crystals. • SFG intensity ratios are directly linked to the surface crystallinity. • Higher level of backbone ordering in semi-crystalline films than in amorphous films. [ABSTRACT FROM AUTHOR]

Abstract: CdTe solar cells have reached efficiencies comparable to multicrystalline silicon and produce electricity at costs competitive with traditional energy sources. Recent efficiency gains have come partly from shifting from the traditional CdS window layer to new materials such as CdSe and MgZnO, yet substantial headroom still exists to improve performance. Thin film technologies including Cu(In,Ga)Se2, perovskites, Cu2ZnSn(S,Se)4, and CdTe inherently have many grain boundaries that can form recombination centers and impede carrier transport; however, grain boundary engineering has been difficult and not practical. In this work, it is demonstrated that wide columnar grains reaching through the entire CdTe layer can be achieved by aggressive postdeposition CdTe recrystallization. This reduces the grain structure constraints imposed by nucleation on nanocrystalline window layers and enables diverse window layers to be selected for other properties critical for electro‐optical applications. Computational simulations indicate that increasing grain size from 1 to 7 µm can be equivalent to decreasing grain‐boundary recombination velocity by three orders of magnitude. Here, large high‐quality grains enable CdTe lifetimes exceeding 50 ns. [ABSTRACT FROM AUTHOR]

FeTaCN films were deposited on quartz substrates by cosputtering of Fe and TaC targets at room temperature with different N[SUB2] flow rate ratios in the sputtering gas. The as-deposited films were postannealed in vacuum for 30 min at various temperatures. The effects of annealing temperature on the N[SUB2] flow rate ratio and film thickness on the magnetic properties and microstructure of the film were investigated. X-ray diffraction and transmission electron microscopy analyses show that the as-deposited FeTaCN film has a nanocrystalline structure or mixing phases of nanocrystalline and amorphous. Nanocrystalline as-deposited film with good soft magnetic properties (in-plane coercivity Hc∥= 1∼2 Oe and 4πMs=12-14kG) can be obtained by controlling the N[SUB2] flow rate ratio and film thickness. The soft magnetic properties can be improved by postannealing the as-deposited film at 200-300 °C as the N[SUB2] flow rate ratio is higher than 5 vol %. For the Fe[SUB71.03Ta[SUB 6.1]C[SUB 7.2]N[SUB 15.67] film, the Hc∥ value decreases as the film thickness is increased when the annealing temperature is lower than 400 °C. After annealing at 300 °C, its Hc∥ is about 3.57 Oe as the film thickness is 50 nm and Hc∥ will decrease to 0.18 Oe as the film thickness is increased to 1000 nm. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZB-MnTe thin films are epitaxially grown by MBE in spite of the metastable nature. • High-crystalline quality, atomic surface flatness and sharp interface are yielded. • PL emissions of 4 T 1g (4 G) and 4 T 1 (4 G) related to Mn2+ d - d multiplets are observed. • Two extra PL transitions attributed to STE states are demonstrated below T N. • Dynamics of photoexcited d -electrons are strongly correlated to the AFM transition. Single-crystalline γ -MnTe thin films with zinc-blende structure were grown epitaxially on InP(1 1 1) by molecular beam epitaxy. Two-dimensional growth regime and atomic surface flatness are achieved, and appearance of Laue's oscillation peaks illustrates the superior crystalline quality and interface of γ -MnTe films. A pseudocrystal buffer layer is formed at interface releasing the strain led by the large lattice mismatch between γ -MnTe and InP, and then growth of γ -MnTe films with a perfect lattice evidences the high-quality crystallinity in a fully relaxed state. Photoluminescence (PL) emissions from 4 T 1g (4 G) and 4 T 1 (4 G) related to Mn2+ ions d - d multiplets are observed with their respective activation energies of ∼142.5 meV and ∼323.5 meV. Such high potentials reflecting the nonradiative recombination indicate the thermal stability of these PL. Moreover, two extra PL transitions assigned to be the emissions from self-trapped exciton (STE) states are found below T N. Time-resolved PL (TRPL) spectra at various temperatures indicate that the relaxation dynamics of photoexcited d -electrons is strongly correlated to the antiferromagnetic ordering transition due to the synergy of magnon, phonon and STE states. These findings suggest that introduction of STE states in a material by controlling its magnetic ordering qualifies the competition in optoelectronics devices. [ABSTRACT FROM AUTHOR]

Density Functional Theory (DFT) calculations demonstrate that holes can trap in crystalline and amorphous HfO 2 and Al 2 O 3 in both single- and bipolaron states. Polarons in the crystalline phase have small trapping energies of the order of 0.2 eV. In the amorphous phase, structural precursor sites cause deep hole trapping with trapping energies exceeding 1.2 eV making these states likely candidates for positive charging in oxide films. [ABSTRACT FROM AUTHOR]

We have studied surface passivation on nanopatterned crystalline silicon (c-Si) wafers (280 µm), thin c-Si wafers (25 µm), ultrathin (~1–6 µm) low temperature epitaxial PECVD and epitaxy-free silicon. Nanopatterned front surfaces were produced by combining nanoimprint lithography with dry or wet etching. The impact of the nanopatterning on the effective lifetime is investigated by means of photoconductance and time-resolved microwave conductivity measurements. Passivation of flat ultra-thin monocrystalline layers by a-Si:H demonstrates effective lifetimes of a few µs. Flat, dry and wet etched c-Si wafers were also passivated by hydrogenated amorphous silicon, thus forming a heterojunction interface. The measured effective lifetimes were 2.2 ms for the flat, 484 μs for the dry and 709 μs for the wet etched wafers, respectively. It is noteworthy that despite the plasma damage associated with the dry etching process, the lifetime measured after passivation remains high enough for the targeted ultrathin solar cells. Solar cells fabricated on wafers nanopatterned via wet etching have reached an open circuit voltage as high as the flat sample thus demonstrating the potential of the use of wet etched nanopatterned surfaces for high efficiency solar cells. [ABSTRACT FROM AUTHOR]

The method of X-ray standing wave-structure-sensitive spectroscopy of condensed matter surface and thin films-is described. The theoretical basis of the method and the possibilities of its application for investigation of crystalline and organic nanostructures are considered. [ABSTRACT FROM AUTHOR]

The topological crystalline insulator SnTe has been grown epitaxially on a Bi2Te3 buffer layer by molecular beam epitaxy. In a 30-nm-thick SnTe film, p- and n-type carriers are found to coexist, and Shubnikov-de Haas oscillation data suggest that the n-type carriers are Dirac fermions residing on the SnTe (111) surface. This transport observation of the topological surface state in a p-type topological crystalline insulator became possible due to a downward band bending on the free SnTe surface, which appears to be of intrinsic origin. [ABSTRACT FROM AUTHOR]

Ab initio molecular dynamics simulations have been carried out to investigate quantitatively 'realistic' heating and melting processes of plasma-born hydrogenated silicon clusters due to reactions with atomic hydrogen in a plasma reactor. For H-exposure processes, we have chosen one hydrogenated amorphous silicon cluster (Si15H10) and the 1 nm hydrogenated silicon nanocrystal Si29H24. Our results indicate that the average energy resulting from each H-atom reaction is about the same for both the amorphous and the initially crystalline clusters before the clusters start undergoing their structural transition from the solid to the liquid state. We show that the melting temperature of the Si29H24 nanocrystal is between 1621 and 1668 K and that its complete phase transition takes about 15 ps after the melting temperature is reached. [ABSTRACT FROM AUTHOR]

The inorganic material cobalt selenide (CoSe), in crystalline form, possesses an optimal band gap matchable to the maximum of the solar spectrum, a high optical absorption coefficient and good conductivity. These characteristics make it quite suitable for use as a photo-electrode in solar conversion devices. However, it is difficult to obtain crystalline, uniform and stoichiometric deposits by conventional methods due to the large difference in their melting points. In view of this, we present a facile, low temperature chemical bath deposition route for the synthesis of highly ordered cobalt selenide thin films. Cobalt nitrate, sodium selenosulphate and ammonia were employed for the synthesis. The films were characterized using X-ray diffraction, optical absorbance, photoluminescence, electrical conductivity, scanning electron microscopy and EDS techniques. The analysis revealed a poly-crystalline structure in a stoichiometric, cubic form with a leaf-like morphology. The size and shape of the ‘leaf’ structure was observed to be uniform. A band gap of 1.7 eV was observed. The room temperature photoluminescence spectra displayed a strong, symmetrical peak at 1.7 eV confirming the directness of the band gap, while the conductivity measurements confirmed the semiconducting nature of the film with a single type of conduction mechanism. As per our literature survey on the chemical synthesis, this is the first attempt for the synthesis of poly-crystalline CoSe in thin film form. [ABSTRACT FROM AUTHOR]

Strain relaxation behavior of epitaxial SrRuO3 thin films on (001) LaAlO3 substrates was investigated using high resolution X-ray diffraction. Lattice distortion and dislocation densities were systematically studied with samples under different growth conditions. Reciprocal space maps reveal different strain relaxation behavior in SrRuO3 thin films grown at different temperatures. Two kinds of strain relaxation mechanisms were proposed to understand the growth dynamics, including the evolution of threading dislocations and the tilt of crystalline planes. [ABSTRACT FROM AUTHOR]

The surface work function (WF) and substrate temperature dependence of the NaCl thin-film growth on Ag(001) have been studied by noncontact atomic force microscopy and Kelvin probe force microscopy. In the sub-monolayer range, the NaCl film is composed of large crystalline islands, which decrease in density and increase in size with increasing temperature during deposition. Each island is composed of a large base island 2 monolayers (ML) thick (for T > 343 K), which collects impinging NaCl molecules that form adislands on top. Kelvin probe force microscopy (KPFM) measurements show a reduction of the silver WF by Δφ = φAg -φNaCl/Ag = 0.69±0.03 eV with no dependence on the film thickness (1-6 ML), in agreement with recent theoretical calculations. The previously observed nanometer-sized moiré pattern on islands that are 45° rotated with respect to the silver lattice could be observed in the scanning tunneling microscopy mode. However, no contrast could be obtained in KPFM images. [ABSTRACT FROM AUTHOR]

Nanocrystalline CdO thin films were prepared by sol-gel dip-coating method using a different solution. The as-deposited films were subjected to drying temperature of 120° in air. The prepared films were annealed in different temperatures of 200, 300 and 400 °C. The characterization of samples was carried out by X-ray diffraction, scanning electron microscopy and UV-VIS spectroscopy. Results show that the samples are polycrystalline in nature and the crystallinity of the films improves with temperature. The average grain size is in the range of 19-34 nm. It was observed that the optical parameters of the films were affected by annealing temperature. [ABSTRACT FROM AUTHOR]

Abstract: The influences of solvent solubility and solution aging on the crystallization of poly(3-hexylthiophene) (P3HT) films were investigated. The solubility difference rather than the evaporation rate of solvent determined the final morphology and crystallinity of film. Marginal solvents (toluene and xylene) with large solubility difference caused crystalline aggregations in solutions during the aging process and then densely stacked network-like structures in solid films. Few crystalline aggregates in good solvent chloroform resulted in a thin layer of fibrillar crystals on the substrate, while dot-like crystals deposited on the substrate from good solvent chlorobenzene since no crystalline aggregates formed in the solution. [Copyright &y& Elsevier]

Abstract: Hierarchically structured CaCO3 films were synthesized at atmospheric conditions (room temperature and 1atm) without the use of templates or amphiphilic molecules in this process. The resulting CaCO3 film was formed by self-organization between Ca(OH)2 and aqueous CO2. The building blocks of the CaCO3 film were thought to be CaCO3 primary nanoparticles that aligned to build higher level structures with greater size, called mesocrystals, depending on the additives. The soluble additives played a key role in the control of the morphology, crystallinity, and polymorphism of the CaCO3 film, and the effects strongly depended on the type of additive and their concentrations. The additives used in this study decreased the crystallinity of CaCO3 (calcite) film in the order of glucose>aspartic acid>serine in a manner inversely proportional to the concentration of the additives. In addition, Mg2+, K+, and Na+ ion additives led to the formation of an aragonite phase, the proportion of which increased with the concentration of ions. The threshold concentrations of these ions for the formation of the aragonite phase in CaCO3 film were found to be in the order of Na+ >K+ >Mg2+. [ABSTRACT FROM AUTHOR]

In this work we have synthesized FePtP films using sodium hypophosphite as source material for phosphorous. The surface morphology, crystalline structure, grain size and magnetic properties of the plated films prepared at various current densities, bath temperature and concentration of phosphorous source material (NaH2PO2) have been compared. The results shows that the structural & magnetic properties of this thin film depends on the phosphorus content in the film. When the bath temperature increases the phosphorus content decreases & hence coercivity increases. Also coercivity increases after annealing. Reasons for variation in magnetic properties and structural characteristics were discussed. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) can exist in at least two different phases (an amorphous and one or more crystalline phases), and they can be switched repeatedly between these phases. The different phases have distinctly different physical properties such as electrical conductivity, optical reflectivity, mass density or thermal conductivity. These differences and the repeatability of the switching give these materials the ability to store information. Rewritable compact discs, digital versatile discs, and Blu-ray™ discs store information in thin films of PCMs, using the difference in reflectivity between the phases as the storage mechanism. A novel solid-state memory technology that applies the difference in electrical resistivity is currently being developed, and possible future applications include reconfigurable logic. This article reviews the unique set of properties of PCMs and their current and future applications. [ABSTRACT FROM AUTHOR]

Abstract: A p-type transparent oxide semiconductor, CuGaO2, was grown epitaxially on (111) single-crystalline yttria-stabilized zirconia (YSZ) substrates by pulsed laser deposition (PLD). Single-phase epitaxial films were obtained in narrow conditions: i.e. 725≤ T s ≤780 °C at PO2 =6 Pa, and 3 Pa≤ PO2 ≤6 Pa at T s =750 °C. The electrical conductivity of the as-deposited films was controlled from 3.3×10−5 S∙cm−1 to 1.7×10−2 S∙cm−1 by increasing the oxygen partial pressure from 3 to 6.5 Pa. The hole concentration and Hall mobility of the most conductive film were 5×1017 cm−3 and 0.2 cm2∙V−1∙s−1, respectively. Estimated from the conductivity, the hole concentration was controlled from ∼1014 cm−3 to ∼1017 cm−3 by the oxygen partial pressure. Post-annealing at 1215 °C smoothed the films surface to 0.56 nm in the root-mean-squares roughness and increased the Hall mobility to 0.8 cm2 V−1∙s−1, which is the largest value among CuGaO2 films reported to date. [Copyright &y& Elsevier]

Polycrystalline silicon obtained by the crystallization of thin amorphous silicon films has been an important material for microelectronics technology during the last decades. Many properties are improved in crystallized amorphous silicon compared to the as-deposited polysilicon such as larger grain size, smoother surface, and higher-carrier mobility. In this work, the crystallization of amorphous silicon is investigated by combining transmission electron microscopy (TEM) observations and molecular dynamics calculations. TEM observations on a series of specimens have shown that the majority of the silicon grains are oriented with a $$ {\left\langle {110} \right\rangle} $$ zone axis normal to the surface. In order to understand the crystallization mechanism molecular dynamic simulations were performed. It is found that the $$ {\left\langle {110} \right\rangle} $$ c/amorphous interface exhibits the lowest reduced interfacial energy density while the $$ {\left\langle {111} \right\rangle} $$ c/amorphous has the lowest reduced energy differences per unit interfacial area. The most energetically unfavorable interface is $$ {\left\langle {001} \right\rangle} $$ c/amorphous. [ABSTRACT FROM AUTHOR]

Abstract: Layer transfer processes yield Si films of high electronic quality on low-cost non-Si carriers such as glass: a crystalline Si film grows on a Si–substrate wafer, is detached from that substrate and transferred to a low-cost non-Si device carrier. The substrate wafer is re-used for further growth cycles. Electrochemical etching of a porous Si (PSI) layer system into the substrate wafer enables homoepitaxial growth of monocrystalline Si films and facilitates the detachment of the film. We discuss the potential of crystalline thin-film cells from layer transfer and review the layer transfer work conducted at ZAE Bayern. The sevenfold use of a substrate wafer and the transfer of a 10×10cm2 epitaxial film from a 6″-wafer is demonstrated. A new module process that permits an integrated series connection by a single metallization step is demonstrated to yield a module efficiency of 10%. [Copyright &y& Elsevier]

Abstract: Crystalline silicon thin-film solar cells combine the advantages of the stability and high-efficiency potential of crystalline silicon solar cell technology with the low material utilization of the thin-film solar cell technology. At Fraunhofer ISE the wafer equivalent concept is currently pursued. Within this concept, the active silicon layers are deposited on high-temperature stable substrates. The resulting substrate/layer sandwich can be processed into a solar cell using the same techniques that are used in conventional crystalline silicon wafer solar cell processing, hence the name wafer equivalent. In the present paper we report on how we realized wafer equivalents and explain in detail our development work on processors for both large-area silicon deposition and for zone melting recrystallization. An overview is given on the solar cell results achieved in this area. [Copyright &y& Elsevier]

Abstract: Crystalline silicon on glass (CSG) solar cell technology was developed to address the difficulty that silicon wafer-based technology has in reaching the very low costs required for large-scale photovoltaic applications as well as the perceived fundamental difficulties with other thin-film technologies. The aim was to combine the advantages of standard silicon wafer-based technology, namely ruggedness, durability, good electronic properties and environmental soundness with the advantages of thin-films, specifically low material use, large monolithic construction and a desirable glass superstrate configuration. The challenge has been to match the different preferred processing temperatures of silicon and glass and to obtain strong solar absorption in notoriously weakly-absorbing silicon of only 1.4μm thickness, the thinnest active layer of the key thin-film contenders. A rugged, durable silicon thin-film technology has been developed arguably with the lowest likely manufacturing cost of these contenders and confirmed efficiency for small pilot line modules already in the 8–9% energy conversion efficiency range, on the path to 12–13%. [Copyright &y& Elsevier]

Influence of the CdS window layer on the PV performances of 2-μm thick CdS/CdTe solar cells has been studied as a function of the CdS thickness, dCdS. With a reduction of dCdS from 114 to 95 nm, JSC increases due to an increase in blue response. While, at dCdS<85 nm, the conversion efficiency largely decreases due to a decrease in VOC and FF. The deterioration of the crystallinity of CdTe due to a decrease in the sulfur composition x of the CdTe1−xSx mixed-crystal layer is concluded to be the most possible mechanism for the large decreases in VOC and FF. [Copyright &y& Elsevier]

Abstract: Our investigation demonstrates the role of interfaces for molecular mobility of glasses. Usually, the role of the surface layer is neglected because it contains about 10−8 of the number of molecules of the sample. However, the interface is important in several cases: For the thin films; for the processes taking part at the interface (e.g. surface crystallization) and in the cases when bulk molecules are practically immobile. We define a critical temperature T c, below which surface molecules have more important contribution then the bulk ones. As soon as this happens in the vicinity, or rather below, the glass transition temperature, the samples behave solid like. So, the contribution of the surface mobility is not sufficient to cause changes in human life period but it is large enough to permit tiny changes in historical periods. This could be an explanation why cathedral glasses are a couple of microns thicker at the bottom side. [Copyright &y& Elsevier]

It was found that prolonged high-energy ball-milling of Hilgenstokite (tetracalcium phosphate, TTCP) resulted in a decrease in both particle and crystallite size, leading to a mechanical activation of the compound. This mechanically activated material demonstrated a high reactivity such that, in contrast to highly crystalline TTCP, a setting reaction with water to nanocrystalline hydroxyapatite (HA) and Ca(OH)2 could be achieved at 37°C. However, crystalline TTCP is practically unreactive at physiologic temperatures because of the formation of a thin HA layer on the particle surface preventing further reaction. [ABSTRACT FROM AUTHOR]

The correlation between the vicinal properties of SrTiO[sub 3] (001) substrates and the twinning in YBa[sub 2]Cu[sub 3]O[sub 7-x] thin films grown by pulsed-laser deposition is studied using x-ray diffraction with reciprocal space mapping. The vicinal properties, i.e., angle and in-plane orientation, play a significant role in the anisotropic strain starting at the interface between substrate surface and film, and affect the twin behavior of YBa[sub 2]Cu[sub 3]O[sub 7-x]. On substrates having an [110] in-plane orientation of the step edges, a completely preferred twin pair is observed if the vicinal angle is increased to 0.60°. Whereas on substrates having their step edges oriented along one of the crystallographic axis, the films exhibit a detwinning as the vicinal angle increases. For α=1.10° a maximum detwinned, i.e., monocrystalline film is obtained. At this angle, the diffusion length of YBa[sub 2]Cu[sub 3]O[sub 7-x] during the growth matches the terrace length of SrTiO[sub 3]. Up to this specific angle, the films are grown perpendicular to the optical instead of the crystallographic surface. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have studied the ZrO[sub 2](111)/Ni(111) interface using the ultrasoft pseudopotential formalism within density functional theory. We find that ZrO[sub 2](111) adheres relatively strongly at the monolayer level but thicker ceramic films interact weakly with the Ni-substrate. We argue that the cohesion changes character from dominantly image charge interactions for thick ceramic films to more covalent for monolayer ZrO[sub 2](111) films. We provide an analysis of energetic, structural and electronic aspects of the ZrO[sub 2]/Ni interface as a function of the thickness of the oxide layer. We also address the role of the exchange-correlation density functional parameterization for modeling the oxide and metal/oxide interface and discuss the sensitivity of the supercell approximation for metal/oxide interface properties. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Provides information on a study which created a unique type of two dimensional (2D) isotropic media with crystalline texture in the magnetic layer. Intrinsic signal-to-noise ratio, cross track noise and texture-induced modulation noise; Thin-film media demanded by increasing linear and track density; Comparison of 2D-isotropic media with oriented and three dimensional random isotropic media.

Examines the interfaces of YBa[sub 2]Cu[sub 3]O[sub 7-delta] thin films on Si substrates with Y-stabilized ZrO[sub 2] and Y[sub 2]O[sub 3] buffer layers by high-resolution electron microscopy. Discovery of amorphous silica layer at the Si-YSZ interfaces; Presence of planar faults in the Si substrate; Occurrence of misfit dislocations.

The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2 K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular field model of a σπ − d exchange analogous to sp-d interactions in Diluted Magnetic Semiconductors (DMS) renders an enhanced Zeeman splitting and a modified g-factor of −4 for the electrons that mediate the interaction. These studies define an experimental tool for identifying electronic states involved in spin-dependent exchange interactions in organic materials. [ABSTRACT FROM AUTHOR]

A zinc oxide thin film in cubic crystalline phase, which is usually prepared under high pressure, has been grown on the MgO (001) substrate by a three-step growth using plasma-assisted molecular beam epitaxy. The cubic structure is confirmed by in-situ reflection high energy electron diffraction measurements and simulations. The x-ray photoelectron spectroscopy reveals that the outer-layer surface of the film (less than 5 nm thick) is of ZnO phase while the buffer layer above the substrate is of ZnMgO phase, which is further confirmed by the band edge transmissions at the wavelengths of about 390 nm and 280 nm, respectively. The x-ray diffraction exhibits no peaks related to wurtzite ZnO phase in the film. The cubic ZnO film is presumably considered to be of the rock-salt phase. This work suggests that the metastable cubic ZnO films, which are of applicational interest for p-type doping, can be epitaxially grown on the rock-salt substrates without the usually needed high pressure conditions. [ABSTRACT FROM AUTHOR]