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The effect of annealing temperature on the structure, morphology and dielectric properties of La0.75Ba0.25FeO3 compound prepared by the sol-gel method was investigated. The increase of the annealing temperature from 900 to 1100 °C, promotes an increase of the average grain size value. Two dielectric relaxations are detected using the dielectric modulus formalism, attributed to grain and grain boundary relaxations. This behavior was confirmed by both Nyquist and Argand's plots of dielectric impedance and Modulus results at different measuring temperatures. The ac conductivity could be described by Jonscher's power law revealing the presence of both overlapping large polaron tunneling and non-overlapping small polaron tunneling mechanisms.

International audience; N-type organic thin film transistors (OTFT) based on IF(CN2)2-meta were fabricated in bottom gate-bottom contact configuration at substrate temperature of 80 °C and deposition rate dr of 0,4 Å/s, using the epoxy based photoresist SU-8 as gate insulator. A thermal annealing of fabricated devices under nitrogen for 90 min at 150 °C has enhanced their performances. In order to understand the annealing effect on the performance of IF(CN2)2-meta based OFETs, we have analyzed their thermal behavior by characterizing them electrically over a temperature range from 300 up to 380 K while 10 K step was used. Accordingly, we have estimated and compared the activation energy of the mobility Ea and the density of state DOS before and after annealing treatment. The present study has shown that the improvement of OFETs performances is due to the increased crystallinity of IF(CN2)2-meta layer thereby to the enhanced SU-8/IF(CN2)2-meta and Au/IF(CN2)2-meta interfaces. Finally, to understand the charge transport mechanism dominating in the IF(CN2)2-meta molecule and to model the fabricated OFETs, we have successfully reproduced the dependence of mobility with temperature and the transfer and output characteristics using an analytical model based on variable range hopping (VRH) theory.

Made available in DSpace on 2018-12-11T16:52:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-06-15 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) A study of zirconium oxide (ZrO2) thin films obtained by the non-alkoxide sol-gel method at different annealing temperatures, up to 450 °C, is presented. Morphological, compositional, and optical characterizations of zirconia thin films show high transparency and high bandgap, besides homogeneous and non-porous surface. Metal-insulating-metal (MIM) devices were assembled from this zirconia material for electrical characterizations and have shown high electric resistivity and high specific capacitance. A study of the thin film composition shows residues of S and Cl elements from the precursor solution that contributes for reduction of the dielectric constant of the zirconia thin films, even though they still present higher values when compared to SiO2, which is a positive alternative to replace this oxide in electronic devices. A parallel study of MIM assembled on polymeric substrate and annealed at 100 °C also leads to positive results concerning high electrical insulating and capacitance. This study aims the understanding of the relations between annealing temperature and impurities found in sol-gel based thin films, as well as their relations to dielectric characteristics of zirconia thin films that impact the final properties of electronic devices, such as in field effect transistors. São Paulo State University (Unesp) School of Sciences Department of Physics São Paulo State University (Unesp) School of Sciences POSMAT – Post-Graduate Program in Materials Science and Technology São Paulo State University (Unesp) School of Sciences Department of Physics São Paulo State University (Unesp) School of Sciences POSMAT – Post-Graduate Program in Materials Science and Technology FAPESP: 16/16423-6 FAPESP: 16/17302-8

The aim of this study is to investigate annealing effects on the electrical characteristics of aluminum oxide (Al2O3) MOS capacitors. Chemical changes after annealing have been characterized using the Fourier transform infrared spectroscopy prior to detailed electrical investigation. The influence of annealing temperature on electrical characteristics has been investigated by capacitance-voltage (C-V) and conductance-voltage (G/ω-V) curves. Effective oxide trap density (Nox), border trap densities (N2bt), and interface trap densities (Nit) were calculated during the electrical analysis. Remarkable changes in the measurements were observed depending on the annealing temperatures. The obtained results demonstrate that the optimum annealing temperature is 450 °C for the Al2O3-based devices.

In present work, the effect of annealing on dark and photo conductivity as well as the various causes of conduction mechanics in S doped amorphous hydrogenated silicon films (a-Si:H) is discussed. The variation of the dark conductivity as a function of temperature has been carried out on unannealed and annealed (annealed at an optimized temperature of 300 °C) thin film samples and the activation energy of dark conductivity of respective samples was also calculated at different temperatures. The Study concludes that at high temperatures, an activated type mechanism is responsible for conduction in the a-Si:H films.

International audience; n-type 6H-SiC(0001) substrates were implanted with a fluence of Mn+ 5x 10(16) (maximum Mn content of 7%), with implantation energy of 80 keV and substrate temperature of 365 degrees C to promote recrystallization. The samples were characterized using Rutherford backscattering and channeling (RBS/C) spectroscopy and electron probe microanalysis in the energy dispersive X-ray (EPMA-EDX) technique; while the magnetization was studied using a superconducting quantum interference device techniques. In the as-implanted sample, three well-defined specific defect zones were identified as deduced from the analysis of RBS/C spectra. It is shown that the two main vacancy-related and interstitial-related defects undergo limited changes when annealing at 800 degrees C, while a major recovery is obtained after annealing at 1100 degrees C. Strain relaxation was also observed upon annealing as determined from HRXRD. Magnetization was strongly reduced with increasing annealing temperature from 800 degrees C to 1600 degrees C. This effect seems to be related to the dilution effect (reduction of Mn content) due to the local diffusion of Mn as suggested from the results obtained using both RBS/C and EPMA-EDX techniques.

Polycrystalline 0.2at%Pr:Lu3Al5O12 (Pr:LuAG) transparent ceramics were fabricated by solid-state reaction using 0.01 wt% MgO as sintering aid. The as-sintered ceramics were annealed in air at different temperatures. Optical absorption, photoluminescence, X-ray excited luminescence and pulse height spectra obtained after different annealing were compared. Modifications of the oxygen vacancy concentrations are found to govern the changes of the optical and scintillation response for annealing temperatures lower than 1000 °C, while the oxidation of Pr3+ to Pr4+ plays a more important role for higher temperatures. Air annealing up to 700 °C is an effective tool to improve the 5d-4f emission efficiency of MgO co-doped Pr:LuAG transparent ceramics. The highest radioluminescence intensity is obtained for the 700 °C annealed sample. At variance, higher temperature annealing leads to the deterioration of 5d-4f photoluminescence and scintillation properties because of the self-absorption of Pr4+ and energy transfer from Pr3+ to Pr4+. In addition, we find that the 4f-4f slow emission of ceramics shows different response characteristics under different irradiation sources.

In this study, Mn3O4 thin film was prepared by the chemical bath deposition (CBD) method on commercial microscope glass substrate deposited at 30° C. The Mn3O4 film was annealed in an air atmosphere for an hour at temperatures 100° C, 200° C, 300° C, 400° C, 500° C, respectively. The effect of annealing temperature on structural and optical properties such as optical constants of extinction coefficient (k), refractive index (n), the real (?1) and imaginary (?2) part of the dielectric constant and energy band gap (Eg) of the film were determined. The experimental characterization techniques included X-ray diffraction (XRD), UV-vis spectrophotometer and Hall effect measurement. XRD analysis showed that the film is grown in a polycrystalline structure in tetragonal phase. The conductivity of the film as a function of annealing temperature was measured as (1.32-6.65)×10-6 (?cm)-1. © 2016 The Authors.

Thin polycrystalline zinc-doped indium oxide (In2O3–ZnO) films were prepared by post-annealing amorphous films with various weight concentrations x of ZnO in the range 0x 0.06. We have studied the dependences of the resistivity ρ and Hall coefficient on temperature T and magnetic field H in the range 0.5T 300 K, H6 Tfor 350 nm films annealed in air. Films with 0x0.03 show the superconducting resistive transition. The transition temperature Tc is below 3.3 K and the carrier density n is about 1025–1026 m−3. The annealed In2O3–ZnO films were examined by transmission electron microscopy and x-ray diffraction analysis revealing that the crystallinity of the films depends on the annealing time. We studied the upper critical magnetic field Hc2 (T) for the film with x = 0.01. From the slope of dHc2 /dT, we obtain the coherence length ξ (0) ≈ 10 nm at T = 0 K and a coefficient of electronic heat capacity that is small compared with those of other oxide materials.