Function Of Post-annealing Temperature Research Articles

Evolution of strong second-order magnetic anisotropy in Pt/Co/MgO trilayers by post-annealing

In this study, the first- (K1) and second-order (K2) magnetic anisotropies are investigated as a function of post-annealing temperature (Ta) in Pt/Co/MgO heterostructures. We find that both extrinsic and intrinsic mechanisms contribute to K2 with their relative contributions significantly depending on the quality of the Co/MgO interface, which is sensitively affected by the Ta value. In contrast with previous studies that mainly considered the extrinsic effects on K2, we obtain high K2 values of up to 2.04 × 106 erg/cm3 for the stack annealed at Ta = 400 °C by maximally utilizing the intrinsic effect at the Co/MgO interface, thus facilitating robust easy-cone anisotropy. We also demonstrate that the canted magnetization can be efficiently manipulated by the spin–orbit torques generated from the Pt layer, which is an important step toward the application of easy-cone states in various spintronic devices.

The role of post annealing temperature on a facile synthesis of 2D h-BN nanoflowers

Nanocrystalline hexagonal boron nitride (h-BN) nanoflowers have been synthesized by a facile mixing annealing approach. Here, the nontoxic precursor (boric acid and urea) under Ar-atmosphere and various annealing temperature (1000 °C, 1100 °C, and 1200 °C) were responsible for nanoflowers kind structure. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM) and UV–Vis spectroscopy. The observed results indicated that the optical and other physical properties of the prepared material were found to be as a function of post-annealing temperature.

Effect of thermal evolution of point defects on the electrical properties of nitrogen-implanted ZnO thin films

Raman backscattering spectroscopy and X-ray photoelectron spectroscopy have been applied to study thermal evolution of point defects as a function of post-annealing temperature in nitrogen-implanted ZnO thin films (ZnO:N). Zni-related donor defects (e.g., Zni-NO complexes or Zni clusters) are prone to dissociation to form a freely moving isolated Zni defect by post-annealing process, which is extremely advantageous for achieving a p-type transition of the ZnO:N film. However, lots of Ni atoms induced by ion implantation could migrate to the near-surface of the films to form NC/NH/NO species with increasing post-annealing temperature, resulting in a lower concentration of NO acceptor defects in ZnO:N films. In addition, although post-annealing at higher temperatures can form more No acceptor defects, the newly generated (N2)O double donor defects have a severe self-compensating effect. Consequently, the concentration of both the Zni-related donors and effective acceptors gradually decreases at elevated post-annealing temperatures, which is the reason why all ZnO:N films present n-type conductivity and do not convert to p-type conductivity.

Phase transformation in tungsten oxide nanoplates as a function of post-annealing temperature and its electrochemical influence on energy storage

The morphology and crystal structure of electrode materials have an enormous impact on their electrochemical properties for employment in supercapacitors for various applications. In this study, the transformations of the crystal structure of WO3·H2O nanoplates were conducted by post-annealing at 200 °C and 400 °C. The morphological and structural evolution of the electrodes was studied via FEG-SEM, HRTEM, FTIR, XRD, and Raman spectroscopy. The phase transition and enhanced degree of crystallinity were observed with increasing temperature. The orthorhombic structures of the hydrate WO3·H2O (W80), the mixed-phase with mesoporous structure (W200), and finally the monoclinic phase of WO3 structures (W400) were achieved at annealing temperatures of 80 °C, 200 °C, and 400 °C respectively. The electrochemical performance of electrode W200 showed the highest specific capacitance of 606 F g−1 as compared to electrode W80 (361 F g−1), and was two-fold greater than electrode W400 (302 F g−1) at a current density of 1 A g−1. Moreover, electrode W200 exhibited excellent cyclic stability of 89% at an ultrahigh scan rate of 100 mV s−1 after 4000 cycles. The results highlight that the mixed-phase WO3 nanoplates would make a suitable electrode material for supercapacitors with desired electrochemical features.

Enhancing the local conductivity of Cu films using temperature-assisted agglomerated Cu nanostructures

We investigate the structural and electrical properties of Cu film and reveal their changes as a function of post-annealing temperature. Thermal annealing of a Cu film on a dielectric substrate can improve its crystallinity; however, high-temperature annealing also leads to a morphological transformation that hinders the precise measurement of electrical properties. The enhanced crystallinity of the Cu films is verified with x-ray diffraction as the annealing temperature increases. To examine the electrical properties of the Cu film after the dewetting processes, which promotes the formation of voids and agglomerations, we utilize both conventional micro four-point probe method as well as an advanced four-point probe scanning tunneling microscopy (4P-STM) technique to measure the conductance and evolution of the microscopic structural properties. We could eliminate a deceptive effect of voids with 4P-STM technique, and disclosed a significantly reduced resistivity (1.88 ± 0.07 µΩ·cm) of Cu nanostructure after post-annealing at 700 °C. We unveiled impact of crystallinity and imperfections of Cu nanostructure, and discussed the critical role of the twin grain boundaries of single-crystalline Cu (1 1 1) on an Al2O3 substrate. We anticipate that understanding the evolution of the structures and the enhanced electrical properties of the post-annealed Cu nanostructures would be important for nanoscale devices where Cu is used as an interconnecting material and could provide a new route to control the plasmonic applications.

Plasmonic Resonance In Spray Deposited Au Nanoparticles Grown On TiO2 Thin Film

Gold nanoclusters embedded in titania (TiO2) matrix were synthesized by thermal spray method followed by thermal annealing in an inert atmosphere. The effect of annealing temperature on the plasmonic response and optical properties of gold nanocluster in titanium dioxide matrices have been investigated by using UV-visible absorption spectroscopy. The surface plasmon resonance (SPR) at metal-dielectric interface for gold nanoparticles has been observed for as deposited samples at 561.8 nm which degrade as a function of post annealing temperature. Field emission scanning electron micrographs confirm the presence of spherical nanoparticles whose size increases with post annealing temperature. The plasmonic resonance of noble metals at nanoscale is fundamentally and technologically important for light trapping photovoltaic and other applications.

Influence of post-annealing on the off current of MoS2 field-effect transistors.

Two-dimensional materials have recently been spotlighted, due to their unique properties in comparison with conventional bulk and thin-film materials. Among those materials, MoS2 is one of the promising candidates for the active layer of electronic devices because it shows high electron mobility and pristine band gap. In this paper, we focus on the evolution of the electrical property of the MoS2 field-effect transistor (FET) as a function of post-annealing temperature. The results indicate that the off current drastically decreased at 200°C and increased at 400°C while other factors, such as the mobility and threshold voltage, show little variation. We consider that the decreasing off current comes from the rearrangement of the MoS2 film and the elimination of the surface residue. Then, the increasing off current was caused by the change of the material's composition and adsorption of H2O and O2.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-0773-y) contains supplementary material, which is available to authorized users.

Effect of post-annealing temperature on the dielectric function of solution-processed LaAlO x /Si Films

We report the optical properties of amorphous LaAlOx (LAO) films grown by using the sol-gel process. The dielectric functions e of the LAO films are obtained from 0.7 to 8.6 eV as a function of post-annealing temperature using spectroscopic ellipsometry. The LAO precursor sols were prepared at a molar ratio of La:Al = 1:1, were deposited on p-type Si substrates, and were sintered at 400 °C. Post-annealing was performed for 1 min in N2 by rapid thermal annealing (RTA) at 700, 850, and 1000 °C. The e spectra of the resulting LAO films were obtained from the measured pseudodielectric functions by using multilayer calculations with the Tauc-Lorentz dispersion relation. We found that the values of e for the sol-gel-deposited LAO films depended on the RTA temperature. This dependence provides a fundamental tuning basis for the solution-processed manufacture of LAO devices.

The effect of Al2O3 passivation layer in pulsed-laser-deposited ZrO2 films on n-GaAs substrate as a function of post-annealing temperature

We investigated the thermal stability of ZrO2/GaAs structures deposited by pulsed laser deposition as a function of the post-annealing temperature. During the annealing process the interfacial layer between the pulsed laser deposited ZrO2 thin film and GaAs substrate increased significantly at the temperature of 500°C, and the ZrO2 thin film became fully crystallized to the monoclinic phase at the temperature of 600°C. This resulted in the degradation of electrical properties such as the leakage current and the breakdown voltage, and an interfacial trap charge density. In order to improve the thermal stability, we pre-deposited an Al2O3 passivation layer by atomic layer deposition followed by pulsed laser deposited ZrO2 deposition. The amorphous Al2O3 passivation layer hindered the crystallization of the ZrO2 thin film during the annealing process, significantly improving the electrical characteristics of the resulting structure compared to the ZrO2/GaAs structures without an Al2O3 passivation layer. In particular, the interfacial reaction was effectively suppressed up to a temperature of 600°C so that the interface trap charge density was significantly decreased due to the low oxygen diffusivity of Al2O3 layer.

Structural and magnetic properties of epitaxial Heusler alloy Fe2Cr0.5Co0.5Si

This paper reports the study of structural and magnetic properties of Heusler alloy Fe2Cr0.5Co0.5Si (FCCS) thin film and its tunnel magnetoresistance (TMR) effect. The smooth quaternary Heusler alloy FCCS film with surface roughness of rms value of 0.25 nm measured by atomic force microscopy and partial L21 phase was obtained by magnetron sputtering at room temperature followed by in-situ annealing at 400 °C. The saturation magnetization and coercivity of FCCS are 410 emu/cm3 and 20 Oe, respectively. The magnetic tunnel junctions (MTJs) using FCCS as free layer were studied in detail as a function of post-annealing temperature. A TMR ratio of 15.6% has been achieved with 300 °C post-annealing. This is about twice the highest TMR ratio obtained in MTJs using Fe2CrSi. The enhancement of TMR ratio can be attributed to the successful tuning of the Fermi level of Fe2CrSi close to the center of the minority band gap by Co-doping.

Thermal studies of soda glass metal nanocomposite synthesized by ion exchange

Soda glass metal nanocomposite having Ag nanoparticles has been synthesized by the combined use of ion exchange method and subsequent thermal annealing. Remarkable changes in photoluminescence and UV-Visible spectra of resulting nanocomposite as a function of post annealing temperature has been observed. These changes can be attributed to the structural rearrangement of silver during heat treatment. In UV-Visible spectra, characteristic surface plasmon resonance peak of silver nanoparticles has been observed around 430 nm. Photoluminescence spectra of the silver exchanged soda glass samples show a dominant peak at 547 nm. At an annealing temperature of 450°C photoluminescence intensity is the maximum followed by a decreasing trend upto 600°C.

Electrical, structural and optical characterization of copper oxide thin films as a function of post annealing temperature

AbstractCopper oxide thin films were obtained by annealing (temperature ranging between 100 and 450 °C) the metallic Cu films deposited on glass substrates by e‐beam evaporation. XRD studies confirmed that the cubic Cu phase of the as‐deposited films changes into single cubic Cu2O phase and single monoclinic CuO phase, depending on the annealing conditions. The crystallite size is varied between ∼12 and 31 nm. The lattice parameters of cubic Cu and Cu2O phases are estimated to ∼3.60 and ∼4.26 Å, respectively. The films with Cu2O phase showed p‐type characteristics. The conductivity is decreased linearly with the decreasing temperature (1/T), which has confirmed the semiconductor nature of the deposited films. The calculated activation energy is varied between 0.10 and 0.16 eV. The surface microstructure is changed depending on the variation in the annealing temperature. The poor transmittance of the as‐deposited films (<1%) is increased to a maximum of ∼80% (800 nm) on annealing at 200 °C. The estimated direct allowed band gap is varied between 1.73 and 2.89 eV.

Changes in the structure of an atomic-layer-deposited HfO2 film on a GaAs (100) substrate as a function of postannealing temperature

The effects of postannealing temperature on the crystal structure and energy band gap (Eg) values of atomic-layer-deposited HfO2 films grown on a GaAs (100) substrate were investigated. In postannealed HfO2 films prepared using a rapid thermal annealing (RTA) process in a N2 ambient at temperatures over 600 °C, the initially produced, partially crystallized HfO2 film changed into a well-ordered crystalline structure with no detectable interfacial layer between the film and the GaAs substrate. In the case of a RTA prepared at 700 °C, the thickness of the film was relatively increased compared to that of an as-grown film. Changes in the depth profile data related to stoichiometry and electronic structure after the annealing treatment indicated that Ga oxide is formed within the HfO2 film during the RTA. The formation of Ga oxide in the film significantly affected the Eg values, i.e., the Eg changed from 5.5 for an as-grown film to 4.7 eV for a film annealed at 700 °C.

Correlation between diffraction patterns and surface morphology to the model of oxygen diffusion into ITO films

Indium tin oxide (ITO) films post-annealed in air usually have higher resistivity compared to the ITO films post-annealed in vacuum. This is likely due to the incorporation of oxygen atoms into the ITO films during post-annealing treatment in air. In this paper, we studied mainly the electrical properties of ITO films as a function of post-annealing temperature and post-annealing ambient. Our results show that the ITO films post-annealed in vacuum have lower resistivity compared to the ITO films post-annealed in air. From the results, we relate the model of oxygen diffusion with the AFM images and the (4 0 0)/(2 2 2) XRD peak ratio. We observe that the ITO films post-annealed in vacuum have larger grain size through the AFM images. The reduction of grain boundary scattering leads to higher conductivity. Furthermore, the ITO films post-annealed in vacuum have rather constant (4 0 0)/(2 2 2) XRD peak ratio. This result indicates that there is less oxygen atoms diffuse into the ITO films in vacuum. The ITO film post-annealed at 500 °C in vacuum has a grain size of ∼125 nm and resistivity of ∼3.49 × 10 −4 Ω cm.

Post annealing effects on the properties of sputtered nano‐crystallite indium tin oxide thin films on flexible polyimide substrate

AbstractIndium tin oxide (ITO) thin films were deposited onto flexible polyimide substrates using RF sputtering system at room temperature. The deposited films were then heat treated at different temperatures in air and vacuum atmospheres. The structural variations and as consequence the electro‐optical characteristic variations of the films were systematically investigated as a function of post annealing temperature and atmosphere. The structure of the films was studied by means of XRD and SEM techniques and the electro‐optical characteristics were measured by four point probe and spectrophotometer, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Preparation and electrical properties of highly (1 1 1) oriented antiferroelectric PLZST films by radio frequency magnetron sputtering

Highly (1 1 1) oriented lead lanthanum zirconate stannate titanate (PLZST) films were synthesized on Pt/Ti/SiO 2/Si substrates by radio frequency (RF) magnetron sputtering. The microstructure and electrical properties of the films were investigated as a function of post-annealing temperature. Smooth and crack-free films obtained by post-annealing at 700 °C for 30 min, and exhibit a dense columnar microstructure with a grain size of ∼0.85 μm. The sputtered PLZST films of nominal composition Pb 0.97La 0.02 (Zr 0.60Sn 0.30Ti 0.10)O 3 display a high saturation polarization of ∼70 μC cm −2, a low antiferroelectric-to-ferroelectric switching field (<100 kV cm −1), a reasonable dielectric constant and a low loss tangent. This combination of properties makes them attractive for microdevice applications.

An electrostatic force microscope study of Si nanostructures on Si(1 0 0) as a function of post-annealing temperature and time

The evolution of Si nanostructures induced by Ar + ion sputtering on Si(1 0 0) was studied with electrostatic force microscopy (EFM) as a function of post-annealing temperature ( T = room temperature–800 °C) and time ( t = 0–160 min). The post-annealing of the nanostructure was conducted in vacuum. It was found that with T increasing, the EFM contrast degraded steadily and became nearly undetectable at T = 800 °C; with t increasing at T = 800 °C, the EFM contrast fell down steadily as well. However, the surface morphology and roughness were much less affected after annealing. The results suggest that the as-formed Si nanostructures may not be epitaxially grown on Si(1 0 0) substrate as claimed before. A plane capacitance model supported this conclusion.

Optical Absorption and Photoluminescence Spectroscopy of the Growth of Silver Nanoparticles

Results obtained from the optical absorption and photoluminescence (PL) spectroscopy experiments have shown the formation of excitons in the silver-exchanged glass samples. These findings are reported here for the first time. Further, we investigate the dramatic changes in the photoemission properties of the silver-exchanged glass samples as a function of postannealing temperature. Observed changes are thought to be due to the structural rearrangements of silver and oxygen bonding during the heat treatments of the glass matrix. In fact, photoelectron spectroscopy does reveal these chemical transformations of silver-exchanged soda glass samples caused by the thermal effects of annealing in a high vacuum atmosphere. An important correlation between temperature-induced changes of the PL intensity and thermal growth of the silver nanoparticles has been established in this Letter through precise spectroscopic studies.

Crystallization Dynamics Of Ferroelectric Pzt (52/48) Thin Film Prepared By Reactive Cosputtering On Pt On Si(100)

ABSTRACTThe crystallization process and microstructural evolution of PZT (52/48) thin films deposited on Pt thin film electrode on Si (100) by reactive multitarget cosputtering technique have been studied as a function of post-annealing temperature and holding time. As annealing temperature increases, the Amorphous PZT films as-deposited at low substrate temperature of 200 °C crystallize into pyrochlore at 450 °C and ferroelectric perovskite phase with pseudo-cubic structure at 550 °C in sequence. X-ray diffraction data show crystallization into perovskite phase to be complete in 30 Minutes at 550 °C. Furthermore, the change of PZT/Pt/Ti/SiO2/Si interfacial TEM Morphology during heat-treatment has been closely scrutinized.