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In this work, we analyze the electrical behavior of strontium ferromolybdate below room temperature. We demonstrate that in SFMO ceramics, SFMO thin films deposited by pulsed laser deposition including (100) and (111) textured thin films, as well as in nonstoichiometric SFMO ceramics, an intergrain tunneling mechanism of charge carrier conduction leads to a decrease in resistivity with increasing temperature in the low-temperature region. This intergrain tunneling can be attributed to fluctuation-induced tunneling. On the other hand, bulk metallic resistivity of the grains, which increases with temperature, becomes dominant at higher temperatures and magnetic fluxes. The interplay of these conduction mechanisms leads to a resistivity minimum, i.e., a resistivity upturn below the temperature of minimum resistivity. Several mechanisms have been discussed in the literature to describe the low-temperature upturn in resistivity. Based on available literature data, we propose a revised model describing the appearance of a low-temperature resistivity minimum in SFMO ceramics by an interplay of fluctuation-induced tunneling and metallic conductivity. Additionally, we obtained that in the region of metallic conductivity at higher temperatures and magnetic fluxes, the pre-factor Rm of the temperature-dependent term of metallic conductivity written as a power law decreases exponentially with the temperature exponent m of this power law. Here, the value of m is determined by the charge scattering mechanism. [ABSTRACT FROM AUTHOR]

Characterization of thermoelectric transport properties for temperature sensing, cooling, and energy harvesting applications is necessary for a reliable device performance in progressively minimized computer chips. In this contribution, we present a fully automated thermovoltage and sheet resistance measurement setup, which is calibrated and tested for the production of silicon- and silicon-germanium-doped as well as silicide complementary metal–oxide–semiconductor-compatible thin films. A LabVIEW-programmed software application automatically controls the measurement and recording of thermovoltages at individually defined temperature set points. The setup maps average temperature and temperature differences simultaneously in the regime from 40 to 70 °C. The Seebeck coefficient calculated by means of the inversion method was used to eliminate the offset voltage influence. Finally, we present and discuss the Seebeck coefficient as well as the sheet resistance for application-specific different temperature set points of several doped poly-Si, poly-SiGe, and silicides. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy was used to study the direct synthesis of strontium and molybdenum oxide thin films deposited by multitarget reactive magnetron sputtering (MT-RMS). Sr and Mo targets with a purity of 99.9% and 99.5%, respectively, were co-sputtered in an argon–oxygen gas mixture. The chamber was provided with an oxygen background flow plus an additional controlled oxygen supply to each of the targets. We demonstrate that variation in the power applied to the Mo target during MT-RMS enables the production of strontium and molybdenum oxide films with variable concentrations of Mo atoms. Both molybdenum and strontium were found in the oxidized state, and no metallic peaks were detected. The deconvoluted high-resolution XPS spectra of molybdenum revealed the presence of several Mo 3d peaks, which indicates molybdenum bonds in a lower valence state. Contrary to the Mo spectra, the high-resolution strontium Sr 3d spectra for the same samples were very similar, and no additional peaks were detected. [ABSTRACT FROM AUTHOR]

The incessant downscaling of building blocks for memory and logic in computer chips requires energy-efficient devices. Thermoelectric-based temperature sensing, cooling as well as energy harvesting could be useful methods to reach reliable device performance with stable operating temperatures. For these applications, complementary metal–oxide–semiconductor (CMOS)-compatible and application ready thin films are needed and have to be optimized. In this work, we investigate the power factor of different phosphorous-doped silicon germanium (SiGe) films fabricated in a 300 mm CMOS-compatible cleanroom. For the thermoelectric characterization, we used a custom-built setup to determine the Seebeck coefficient and sheet resistance. For sample preparation, we used low pressure chemical vapor deposition with in situ doping and subsequent rapid thermal annealing on 300 mm wafers. Thin film properties, such as film thickness (12–250 nm), elemental composition, crystallinity, and microstructure, are studied via spectroscopic ellipsometry, x-ray photoelectron spectroscopy, x-ray diffraction, atomic force microscopy, and TEM. The SiGe-based thin films vary in the ratio of Si to Ge to P and doping concentrations. A power factor of 0.52 mW/m K2 could be reached by doping variation. Our results show that SiGe is a very attractive CMOS-compatible material on the 300 mm wafer level and is immediately ready for production of thermoelectric embedded applications. [ABSTRACT FROM AUTHOR]

This work reviews some fundamental issues that are relevant for the fabrication of stable‐phase strontium ferromolybdate thin films. The main challenges for strontium ferromolybdate thin film deposition arise from the sensitivity of the material's magnetic properties to point defect formation: i) Antisite defect formation and oxygen nonstoichiometry should be avoided by precise composition control during film manufacturing; ii) a highly ordered state of the correct phase and B‐site cation valence will be obtained only in a very narrow window of growth conditions; iii) to avoid additional antisite disorder with decreasing synthesis temperature, the effective temperature at the film surface should be increased by an energy flux to the growing film surface. Since thin film deposition is nonequilibrium in nature, the review starts with the consideration of equilibrium phase stability. Cation and oxygen stoichiometries are analyzed with regard to their effect on key magnetic properties. Film strain formed due to thermal and lattice mismatch is of great concern since it influences the choice of the substrate. Finally, thin film deposition techniques are valued for their benefits in strontium ferromolybdate thin film technology. [ABSTRACT FROM AUTHOR]

Glancing angle deposition (GLAD) is a physical vapor deposition (PVD) process using a substrate that rotates tilted at an angle to the evaporation source. Depending on the deposition conditions, it provides the controlled formation of regular nanostructures during the PVD process. As a result, a wide variety of shapes, such as spirals or vertical columns, can be easily fabricated in the nanometer range. For this reason, GLAD has already been proven reliable in the production of optical coatings with very low reflectance in a broad spectral range. This paper examines the morphology of tantalum nanostructures deposited on planar silicon substrates by electron beam evaporation. The prepared samples are characterized by scanning electron microscope (SEM) images at a breaking edge with respect to the layer structure and by focused ion beam (FIB) SEM images of the cross-sectional areas with respect to the porosity. The porosity can be used to model the optical properties of the thin film with the effective medium theory (EMT). Our work studies the relationship between the evaporation parameters (growth pitch and deposition angle) and thin film morphology of tantalum so that in future work the optical properties can be linked to the deposition parameters, which in turn can be chosen to achieve highly absorbent infrared radiation layers, e.g., for infrared sensors. It was shown that the porosity across the film thickness of both columnar and screw-like thin films is nearly constant, whereas the porosity profiles of spiral structures show a periodic pattern, the period of which seems to depend on the growth pitch. [ABSTRACT FROM AUTHOR]

In this work, we consider the electrocaloric effect in relaxor ferroelectrics above the temperature of the dielectric constant maximum. For the purpose of modelling, a modified Curie--Weiss law was adapted to approximate the complex physics of relaxors. The requirements to electrocaloric materials derived on this basis are fulfilled by relaxor single crystals, ceramics and high-quality thin films. Relaxor ferroelectrics exhibit a suitable electrocaloric performance starting at applied electric fields of about 25 V/μm. [ABSTRACT FROM PUBLISHER]

In this work, a ferroelectric domain-enhanced electron emission mechanism is proposed. The polarization distribution near 900 domain walls is calculated by solving a set of second order differential equations, including the Poisson's one and equations derived from an expansion of the free energy Φ(P) in power series of the polarization according to the Devonshire-Landau-Ginzburg theory. Domain walls intersecting the emitting surface cause sufficient electric fields and lower the potential barrier for electron emission. This induces centers of enhanced electron emission. Relaxing domain walls were found to excite trapped excess electrons in front of the wall. [ABSTRACT FROM AUTHOR]

A microwave characterization at UHF band of a ferroelectric hafnium zirconium oxide metal-ferroelectric-metal (MFM) capacitors for varactor applications has been performed. By using an impedance reflectivity method, a complex dielectric permittivity was obtained at frequencies up to 500 MHz. Ferroelectric Hf0.5Zr0.5O2 of 10 nm thickness has demonstrated a stable permittivity switching in the whole frequency range. A constant increase of the calculated dielectric loss is observed, which is shown to be an effect of electric field distribution on highly resistive titanium nitride (TiN) thin film electrodes. The C-V characteristics of a "butterfly" shape was also extracted, where the varactors exhibited a reduction of capacitance tunability from 18.6% at 10 MHz to 15.4% at 500 MHz. [ABSTRACT FROM AUTHOR]

During sensor fabrication, hydrogel thin films of poly(vinylalcohol)/poly(acrylic acid) (PVA/PAA) is exposed to various low pressure plasmas. To conserve the sensing properties of the hydrogel, a precise knowledge of the interaction of the PAA/PVA film with the low-pressure plasmas of the technological cycle is required. In this work, an investigation of the film surface composition, chemical bonding and optical properties of radio-frequency (13.56 MHz) and dual-frequency (13.56 MHz/100 kHz) plasma modified PAA/PVA thin films were carried out. Plasma treatment was performed in a RIE chamber (SF6, CHF3) and a PECVD deposition chamber (SiH4/N2, NH3). To investigate the influence of ion bombardment, a dual-frequency configuration comprising two r.f. power supplies operating in a switched mode was used. The results of this work allow optimizing the fabrication of thin film pH-value sensors. [Copyright &y& Elsevier]