О возможности введения примеси железа в узлы A в SrTiO-=SUB=-3-=/SUB=-

The local environment and oxidation state of the Fe impurity in strontium titanate are studied using XAFS spectroscopy. The influence of annealing temperature and deviation from stoichiometry on the possibility of incorporation of the impurity into the A and B sites of the perovskite structure is studied. The results obtained from the X-ray diffraction, XANES spectra, and EXAFS spectra suggest that at high annealing temperature the iron atoms, at least partially (up to 30%), enter the A sites in SrTiO3. The obtained results agree with results of first-principles calculations, according to which the iron at the A site exhibits strong off-centering (the displacement of ~1 Angstrom), similar to that previously established in SrTiO3 samples doped with Mn and Co.

Enhanced switching ratio of sol–gel-processed Y2O3 RRAM device by suppressing oxygen-vacancy formation at high annealing temperature

Sol–gel-processed Y2O3 films were used as an active-channel layer for RRAM devices. The effect of post-annealing temperature on structural, chemical, and electrical characteristics was investigated. The Y2O3-RRAM devices, comprising electrochemically active metal electrodes, Ag, and Indium tin oxide (ITO) electrodes exhibited the conventional bipolar RRAM device operation. The fabricated Ag/Y2O3/ITO RRAM devices, comprising 500-℃ annealed Y2O3 films, exhibited less oxygen vacancy and defect, which reduced the leakage current and boosted high-resistance state/low-resistance state ratio, more than 10^5, and promising nonvolatile memory properties without deterioration for 100 cycles and 10^4 seconds.

Substrate-dependent differences in ferroelectric behavior and phase diagram of Si-doped hafnium oxide

Non-volatile memories based on ferroelectric hafnium oxide, especially the ferroelectric field-effect transistor (FeFET), have outstanding properties, e.g. for the application in neuromorphic circuits. However, material development has focused so far mainly on metal–ferroelectric–metal (MFM) capacitors, while FeFETs are based on metal–ferroelectric–insulator–semiconductor (MFIS) capacitors. Here, the influence of the interface properties, annealing temperature and Si-doping content are investigated. Antiferroelectric-like behavior is strongly suppressed with a thicker interface layer and high annealing temperature. In addition, high-k interface dielectrics allow for thicker interface layers without retention penalty. Moreover, the process window for ferroelectric behavior is much larger in MFIS capacitors compared to MFM-based films. This does not only highlight the substrate dependence of ferroelectric hafnium oxide films, but also gives evidence that the phase diagram of ferroelectric hafnium oxide is defined by the mechanical stress. Graphic Abstract

Biochar as a low-cost, eco-friendly, and electrically conductive material for terahertz applications

We investigate conducting characteristics of biochar derived from the pyrolysis of a paper at terahertz frequencies. Paper is annealed under temperatures ranging from 600 to 1000 °C to modify structural and electrical properties. We experimentally observe that the terahertz conductivity increases above 102 S/m as the annealing temperature increases up to 800 °C. From structural characterization using energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, we confirm that more graphitic biochars are produced in high annealing temperature, in agreement with the improvement of terahertz conductivity. Our results show that biochar can be a highly promising candidate to be used in paper-based devices operating at terahertz frequencies.

Extensive Analysis on the Effects of Post-Deposition Annealing for ALD-Deposited Al2O3 on an n-Type Silicon Substrate

In this study, an investigation was performed on the properties of atomic-layer-deposited aluminum oxide (Al2O3) on an n-type silicon (n-Si) substrate based on the effect of post-deposition heat treatment, which was speckled according to ambient temperature and treatment applied time. Based on these dealings, a series of distinctions for extracted capacitance and dielectric constant, hysteresis was performed on annealed and nonannealed samples. The interface and border trap responses, including stress behavior after an application of constant voltage for a specific time and surface morphology by X-ray diffraction (XRD) technique, were also analyzed between the two above-mentioned sample types. Based on observation, the annealed samples showed superior performance in every aspect compared with the nonannealed ones. Some unusual behaviors after high annealing temperature were found, and the explanation is the ion diffusion from oxide layer towards the semiconductor. Since a constant voltage stress was not widely used on the metal–oxide–semiconductor capacitor (MOSCAP), this analysis was determined to reveal a new dimension of post-deposition annealing condition for the Al/Al2O3/n-Si gate stack.

The role of annealing in determining the yielding behavior of glasses under cyclic shear deformation

Yielding behavior in amorphous solids has been investigated in computer simulations using uniform and cyclic shear deformation. Recent results characterize yielding as a discontinuous transition, with the degree of annealing of glasses being a significant parameter. Under uniform shear, discontinuous changes in stresses at yielding occur in the high annealing regime, separated from the poor annealing regime in which yielding is gradual. In cyclic shear simulations, relatively poorly annealed glasses become progressively better annealed as the yielding point is approached, with a relatively modest but clear discontinuous change at yielding. To understand better the role of annealing on yielding characteristics, we perform athermal quasistatic cyclic shear simulations of glasses prepared with a wide range of annealing in two qualitatively different systems—a model of silica (a network glass) and an atomic binary mixture glass. Two strikingly different regimes of behavior emerge. Energies of poorly annealed samples evolve toward a unique threshold energy as the strain amplitude increases, before yielding takes place. Well-annealed samples, in contrast, show no significant energy change with strain amplitude until they yield, accompanied by discontinuous energy changes that increase with the degree of annealing. Significantly, the threshold energy for both systems corresponds to dynamical cross-over temperatures associated with changes in the character of the energy landscape sampled by glass-forming liquids.

Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films

In this work, undoped, aluminum-, and gallium-doped ZnO thin films (ZnO-H, AZO-H, and GZO-H, respectively) deposited on soda-lime glass substrates by magnetron sputtering method in a gas mixture of hydrogen and argon are annealed at various temperatures in the range of 200–500°C in air to evaluate the durability of those films under annealing temperature. From photoluminescence spectra, formation of point defects, especially oxygen vacancies, when hydrogen diffuses out of the films at high annealing temperature is exhibited via a significant increase of visible emissions. We find out that carrier concentration and Hall mobility of AZO-H and ZnO-H films dramatically decrease, while those of GZO-H film are still stable as the annealing temperature increased from 200°C to 300°C. We proposed a model for interpreting the thermal durability of GZO-H film that, at an annealing temperature of 300°C, Ga3+ ions located at adjacent Zn sites can push hydrogen atoms, which are broken out of the antibonding sites which are perpendicular to the c -axis (AB┴), into bond center sites paralleled to the c -axis (BC//). The movement of hydrogen from AB┴ to BC// site also gives rise to the durability of electrical properties of GZO-H films at the high annealing temperature.

Static Recrystallization in Aluminum/Graphene Composites

The aim of this work was to analyze the recrystallization behavior of cold rolled Aluminum/graphene composites during annealing. The Aluminum/graphene composite was cold rolled firstly, and then annealed at different temperature (250°C, 300°C, 350°C, 400°C) and for various time (1 h, 2 h, 8 h, 32 h). Full recrystallization did not occur until the annealing temperature was above 300 °C. With annealing temperature increasing from 250 to 300°C, the hardness of the composites decreased from 49.6 to 27.6 HV. Grain growth were not observed at high annealing temperature and longer annealing time, which suggested that Graphene has strong pinning effect on the grain boundary of Aluminum.