Tuning of Optical Properties via Annealing of Bismuth Ferrite (BiFeO3) Thin Films

In this study we are reporting annealing induced optical properties of bismuth ferrite (BiFeO3) thin films deposited on glass substrate via spin coating at 5000 rpm. The structural, optical and surface morphology of BiFeO3 (BFO) thin films have been studied via X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Optical absorption (UV-Vis) and Photoluminescence (PL) spectroscopy. XRD spectra confirm annealing induced phase formation of BiFeO3 possessing a rhombohedral R3c structure. The films are dense and without cracks, although the presence of porosity in BFO/glass was observed. Moreover, optical absorption spectra indicate annealing induced effect on the energy band structure in comparison to pristine BiFeO3. It is observed that annealing effect shows an intense shift in the UV-Vis spectra as diffuse absorption together with the variation in the optical band gap. The evaluated optical band gap values are approximately equal to the bulk band gap value of BiFeO3.

Effects of high-dose Ge ion implantation and post-implantation annealing on ZnO thin films

This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on （0001） sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600 - 900 ℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction （XRD）, photoluminescence （PL）. It was found that the intensities of （002） peak and near band edge （NBE） exitonic ultraviolet emission increased with increasing annealing temperature from 600- 900 ℃. The defect related deep level emission （DLE） firstly increased with increasing annealing temperature from 600 - 750 ℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at ～850℃ and ～750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900 ℃.

Influence of Magnetic Annealing on Properties of SmFe Thin Films

SmFe thin films were prepared by DC magietron sputtering at room temperature and 300 %. The influence of magnetic annealing temperature on the phase structure and magnetic properties was investigated. Results showed that thermal sputtering followed by a heat treatment process helped to obtain a structure with a relatively large fraction of SmFe2. Residual phases observed were α-Fe, Sm2O3, and unknown phases. During the annealing treatment, the intrinsic compressive stress in SmFe films was relieved and could become tensile at higher annealing temperatures. The degree of in-plane anisotropy weakened, and furthermore, the anisotropy transformed into out-of-plane anisotropy.

High Coercive NdFeB Thin Film Obtained by Diffusion Annealing

The magnetic properties and microstructure of diffusion annealed [Ta/Nd/NdFeB/Nd/Ta]thin films have been investigated. The films were deposited on Si substrate with various thickness ratio of Nd/NdFeB layer (R=0～3.3), then diffused and crystallized by annealing at 650℃ for 10 min. The film without Nd layer showed soft magnetic behavior and high content of a-Fe phase. The films with R > =1 showed good hard magnetic properties with the high coercivity of about 20 kOe.

Effects of rapid thermal annealing on the room-temperature NO_2-sensing properties of WO_3 thin films under LED radiation

WO3 thin films were sputtered onto alumina substrates by DC facing-target magnetron sputtering. One sample was rapid-thermal-annealed （RTA） at 600 ℃ in a gas mixture of N2：O2 = 4 ： 1, and as a comparison, another was conventionally thermal-annealed at 600 ℃ in air. The morphology of both was investigated by scanning electron microscopy （SEM） and atomic force microscopy （AFM）, and the crystallization structure and phase identification were characterized by X-ray diffraction （XRD）. The NO2-sensing measurements were taken under LED light at room temperature. The sensitivity of the RTA-treated sample was found to be high, up to nearly 100, whereas the sensitivity of the conventionally thermal-annealed sample was about five under the same conditions. From the much better selectivity and response-recovery characteristics, it can be concluded that compared to conventional thermal annealing, RTA has a greater effect on the NO2-sensing properties of WO3 thin films.

Preparation and Effect of Oxygen Annealing on the Electrical and Magnetic Properties of Epitaxial (0001) Zn_(1-x)Co_xO Thin Films

Epitaxial （0001）-oriented Zn1-xCoxO （x= 0.01, 0.05 and 0.1） thin films were grown on c-sapphire substrates by pulsed laser deposition. The XRD analysis, optical transmittance and XPS measurements revealed that the Co2＋ substituted Zn2＋ ions were incorporated into the lattice of ZnO in Zn1-xCoxO thin films. The electrical properties measurements revealed that the Co concentration had a non- monotonic influence on the electrical properties of the Zn1-xCoxO thin films due to the defects resulted from imperfections induced by Co substitution. The resistivity remarkably increased and the carrier concentration remarkably decreased in Zn1-x CoxO thin films after oxygen annealing at 600 ℃ under 15 Pa O2 pressure for 60 mins. Room-temperature ferromagnetic was observed and the ferromagnetic Co amount was smaller than the nominal Co concentration for Zn1-xCoxO samples before oxygen annealing. After oxygen annealing, the Zn1-x CoxO thin films exhibited paramagnetic behavior. It is suggested that the room-temperature ferromagnetic ofZn1-x CoxO thin films may attribute to defects or carriers induced mechanism.

Effect of Oxygen Concentration and Annealing Theatment on the Optical Properties of the Transparent Conductive CdIn_2O_4 Thin Films

Transparent conductive cadmium indium oxide films (CdIn2O4) were prepared by r.f. reactive sputtering from Cd-In alloy targets under an Ar-O2 atmosphere. Electrical conductivity of the order of 105Ω-1.m-1 and the optical transmission as high as 94% are easily attained by postdeposition annealing treatment. The effects of oxygen concentration in the reactive gas mixture and post-deposition annealing treatment on the optical transmittance as well as optical parameters, such as refractive index (n), extinction coefficient (k), real part (ε') and imaginary part (ε') of the dielectric constant, were studied in the visible and near-infrared region. The highfrequency dielectric constant ε∞ the plasma frequency ωP, and the conduction band effective mass mc of different samples were also investigated

Pulsed-Laser Annealing of NiTi Shape Memory Alloy Thin Film

Local annealing of amorphous NiTi thin films was performed by using an Nd：YAG 1064 nm wavelength pulsed laser beam. Raw samples produced by simultaneous sputter deposition from elemental Ni and Ti targets onto unheated Si （100） and Silica （111） substrates were used for annealing. Delicate treatment with 15.92 W/mm^2 power density resulted in crystallization of small spots; while 16.52 and 17.51 W/mm^2 power densities caused ablation of the amorphous layer. Optical microscopy, scanning electron microscopy, X-ray diffraction and atomic force microscopy were performed to characterize the microstructure and surface morphology of the amorphous/crystallized spot patterns.

X-Ray Radiation Sensing Properties of ZnS Thin Film:A Study on the Effect of Annealing

Chemically synthesized ZnS thin film is found to be a good x-ray radiation sensor. We report the effect of annealing on the x-ray radiation detection sensitivity of a ZnS thin film synthesized by a chemical bath deposition technique. The chemically synthesized ZnS films are annealed at 333, 363 and 393K for 1 h. Structural analyses show that the lattice defects in the films decrease with annealing. Further, the band gap is also found to decrease from 3.38 to 3.21 eV after annealing at 393K. Current-voltage characteristics of the films are studied under dark and x-ray irradiation conditions. Due to the decrease of lattice defects and band gap, the conductivity under dark conditions is found to increase from 2.06 × 10^-6 to 1.69 × 10^-5 S/em, while that under x-ray irradiation increases from 4.13 × 10^-5 to 5.28 ×10^-5 S/cm. On the other hand, the x-ray radiation detection sensitivity of the films is found to decrease with annealing. This decrease of detection sensitivity is attributed to the decrease of the band gap as well as some structural and surface morphological changes occurring after annealing.

Effect of annealing treatment on the structural, optical, and electrical properties of Al-doped ZnO thin films

Highly conductive and transparent Al-doped ZnO （AZO） thin films were prepared from a zinc target containing Al （1.5 wt.%） by direct current （DC） and radio frequency （RF） reactive magnetron sputtering. The structural, optical, and electrical properties of AZO films as-deposited and submitted to annealing treatment （at 300 and 400℃, respectively） were characterized using various techniques. The experimental results show that the properties of AZO thin films can be further improved by annealing treatment. The crystallinity of ZnO films improves after annealing treatment. The transmittances of the AZO thin films prepared by DC and RF reactive magnetron sputtering are up to 80% and 85% in the visible region, respectively. The electrical resistivity of AZO thin films prepared by DC reactive magnetron sputtering can be as low as 8.06 x 10-4 Ωcm after annealing treatment. It was also found that AZO thin films prepared by RF reactive magnetron sputtering have better structural and optical properties than that prepared by DC reactive magnetron sputtering.

The effects of post-thermal annealing on the optical parameters of indium-doped ZnO thin films

Indium-doped ZnO thin films are deposited on quartz glass slides by RF magnetron sputtering at ambient temperature. The as-deposited films are annealed at different temperatures from 400℃ to 800 ℃ in air for 1 h. Transmittance spectra are used to determine the optical parameters and the thicknesses of the films before and after annealing using a nonlinear programming method, and the effects of the annealing temperatures on the optical parameters and the thickness are investigated. The optical band gap is determined from the absorption coefficient. The calculated results show that the film thickness and optical parameters both increase first and then decrease with increasing annealing temperature from 400℃ to 800℃. The band gap of the as-deposited ZnO：In thin film is 3.28 eV, and it decreases to 3.17 eV after annealing at 400℃. Then the band gap increases from 3.17 eV to 3.23 eV with increasing annealing temperature from 400℃ to 800℃.

Effects of annealing temperature on microstructure and ferroelectric properties of Bi_(0.5)(Na_(0.85)K_(0.15))_(0.5)TiO_3 thin films

Bi0.5(Na0.85K0.15)0.5TiO3(BNKT15) thin films were synthesized by metal-organic decomposition(MOD) at annealing temperatures of 650,680,710 and 740℃,and the effects of annealing temperature on the microstructure,dielectric properties,remnant polarization(2Pr) and leakage current density were studied with X-ray diffractometer,atomic force microscope,precision impedance analyzer,ferroelectric analysis station and semiconductor parameter tester.The results show that the thin film annealed at 710℃ exhibits a typical perovskite structure without predominant orientation and a smooth surface with evenly distributed grains.2Pr value(67.4 μC/cm2 under 830 kV/cm) and the leakage current density(1.6×10-6 A/cm2 at 170 kV/cm) for BNKT15 thin film annealed at 710℃ are better than those for thin films annealed at other temperatures.

Effect of Annealing on Structural,Optical and Electrical Properties of CdS Thin Films Grown by ILGAR

CdS thin films were deposited by ILGAR （ ion lay gas reaction） method. The effect of annealing temperature under N2 atmosphere on the structural, chemical, topographical development and optical and electrical properties of CdS thin films was investigated by XRD, SEM, XPS, UV- VIS and two-probe technique. It is found that the cubic-phase of as-deposited CdS film transforms to hexagonal phase with a perfected orientation along （002） plane at 300 ℃ . The band gap decreases with increasing annealing temperature until 300 ℃ , which is consistent with the grain growth. The fall of dark and light resistivitiy is obvious with increasing annealing temperature, corresponding to the continuous grain growth and deviation of stoichiometry at higher temperature. The smooth and uniform surface of as-deposited films becomes rougher through thermal treatment, which is related to grain growth and sublimation of CdS at a higher annealing temperature.

Effect of Post Annealing on the Microstructure and Magnetic Properties of NdFeB/α-Fe/NdFeB Thin Films

A series of nanocomposite thin films, composed of Nd2Fe14B and α-Fe, has been prepared by DC-magnetron sputtering combined ion beam sputtering onto Si (100) substrates. The effects of post annealing on the microstructure and magnetic properties of [NdFeB/α-Fe/NdFeB]-type thin films have been investigated. The X-ray diffraction (XRD) study showed that annealing of the films for 30 min at temperatures 550, 600, 650, 700 ℃ resulted in the appearance of diffraction peaks, characteristic for Nd2Fe14B tetragonal structure, α-Fe and Nd2O3 phases. The investigation using the Vibrating Sample Magnetometer (VSM) with a maximum applied field of 2 T indicated that with the increase of the annealing temperature, the magnetic properties of the multilayer films were improved and reached peak value at 650 ℃ (Hci=41.72 kA·m-1, Mr/Ms=0.4, (BH)max=30.35 kJ·m-3), after which the magnetic properties were decreased greatly. Along with the increase of the thickness of α-Fe layer from Tα-Fe>16 nm, the coercivity Hci, saturation magnetization Ms, and remanence ratio Mr/Ms all declined. As the Atomic Force Microscope (AFM) indicated, after being annealed at 650 ℃ for 30 min, the sample was showed fine surface morphology with grain size 60 nm≤dα-Fe≤80 nm and 100 nm≤dNdFeB≤150 nm.

Effect of annealing temperature on structure and electrochemical properties of LiCoO_2 cathode thin films

LiCoO2 thin films, which can be used as a cathode material in microbatteries, were deposited using radio frequency (r.f.) magnetron sputtering system from a LiCoO2 target and in an O2+Ar atmosphere. The films were characterized by various methods such as XRD, SEM and AFM. The LiCoO2 films were annealed in air at 300, 500, 700 and 800 ℃ respectively. The effect of the annealing temperature on the structure, the surface morphology and the electrochemical properties of the films were investigated. The LiCoO2 thin film deposited at room temperature is amorphous and has smaller grain size. With increasing of annealing temperature, the crystallinity of the films is promoted. When the annealing temperature increases to 700 ℃, the films have a perfect crystalline LiCoO2 phase. The LiCoO2 thin film without annealing has no discharge plateau and small discharge capacity (about 27 μAh·cm-2μm). The discharge capacity increases with the increasing of annealing temperature and reaches 47 μAh·cm-2μm for the film annealed with 700 ℃, which also shows the typical discharge plateau of 3.9 V. The cycle performance of LiCoO2 thin films of as grown and annealed at different temperatures were studied. In the case of the film without thermal treatment, the capacity fading is much faster than that of the film annealed at different temperature, showing about 40% capacity loss only after 25 cycles. However, in the case of the film annealed at 700 ℃, the capacity reaches to steady state gradually and maintained constantly with cycling. After 25 times cycling, the discharge capacity of the film annealed at 700 ℃ decreases to about 36.9 μAh·cm-2·μm, only 0.8% capacity loss per cycle.

The Effects of Annealing and Discharging on the Characteristics of MgO Thin Films Prepared by Ion Beam-Assisted Deposition as a Protective Layer of AC-PDP

This study investigated the effects of annealing and discharging on the characteristics of MgO thin films prepared by ion beam-assisted deposition as a protective layer of AC-PDP. By an annealing process at a temperature of 450 ℃ for more than three hours, the crystallinity of the deposited MgO films was improved, but the surface of the （200）-oriented MgO thin films in the vicinity of the discharge electrodes, especially on the inner sides of the electrodes, was subjected to crack formation to the compressive stress of The failure mechanism of the MgO films plus the additional （200）-oriented MgO films was due compressive stress induced by the differences in the coefficient of thermal expansion between the electrode and the dielectric layer. In the discharging process, all MgO films were eroded unevenly, and the serious erosion occurred near the edges of the discharge electrodes. ATM（atomic force microscopy） images show that the eroded surface of the （200）-oriented MgO thin film is smoother than that of the （111）-oriented fihn. Also, the （200）-oriented MgO thin film shows an improved ability to resist ion erosion compared to the （111）-oriented film.

Effect of annealing process on structures and ferroelectric properties of Ca_(0.4)Sr_(0.6)Bi_(3.95)Nd_(0.05)Ti_4O_(15) thin films

Ca0.4Sr0.6Bi3.95Nd0.05Ti4O15 （C0.4S0.6BNT） ferroelectric thin films were prepared on Pt/Ti/SiO2/Si substrates by sol-gel method. Effect of annealing process （time and temperature） on structures and ferroelectric properties of C0.4S0.6BNT thin film was investigated. The relative intensity of （200） peak increased first then decreased with annealing temperature and became predominant at 800 ℃. In contrast, no evident change could be observed in the （001） peak. The remnant polarization （Pr） and coercive field （Ec） for C0.4S0.6BNT film annealed at 800℃ for 5 min were 21.6μC/cm2 and 68.3 kV/cm, respectively.

Ll_0 FePt thin films with 001crystalline growth fabricated by ZnO addition and rapid thermal annealing

FePt films with a high degree of order S of the L10 structure （S 〉 0.90） and well defined [001] crystalline growth perpendicular to the film plane are fabricated on thermally oxidized Si substrates by the addition of ZnO and a successive rapid thermal annealing （RTA） process. The optimum condition to prepare high-ordering L10 FePtZnO films is 20 vol% ZnO addition and 450 ℃ annealing. The effect of the ZnO additive on the ordering process of the L10 FePtZnO films is discussed. In the annealing process, Zn atoms move to the film surface and evaporate. The motion of the Zn atoms accelerates the intergrain exchange and decreases the ordering temperature.

Effect of annealing temperature on the microstructure and optoelectrical properties of ZnO thin films and their application in self-powered accelerometers

This paper reports a piezoelectric nanogenerator(NG) with a thickness of approximately 80 μm for miniaturized self-powered acceleration sensors. To deposit the piezoelectric zinc oxide(ZnO) thin film, a magnetron sputtering machine was used. Polymethyl methacrylate(PMMA) and aluminum-doped zinc oxide(AZO) were used as the insulating layer and the top electrode of the NG, respectively. The experimental results show that the ZnO thin films annealed at 150℃ exhibited the highest crystallinity among the prepared films and an optical band gap of 3.24 eV. The NG fabricated with an AZO/PMMA/ZnO/stainless steel configuration exhibited a higher output voltage than the device with an AZO/ZnO/PMMA/stainless steel configuration. In addition, the annealing temperature affected the open-circuit voltage of the NGs;the output voltage reached 3.81 V when the annealing temperature was 150℃. The open-circuit voltage of the prepared self-powered accelerometer increased linearly with acceleration. In addition, the small NG-based accelerometer, which exhibited excellent fatigue resistance, can be used for acceleration measurements of small and lightweight devices.

MISCIBILITY AND MORPHOLOGY OF THIN FILMS OF BLENDS OF POLYSTYRENE WITH BROMINATED POLYSTYRENES: EFFECTS OF VARYING THE MOLECULAR WEIGHT, BROMINATION DEGREE AND ANNEALING

Thin films of incompatible polymer blends can form a variety of structures during preparation and subsequent annealing process. For the polymer blend system consisting of polystyrene and poly（styrene-co-p-bromo-styrene）, i.e., PS/PBrxS, its compatibility could be adjusted by varying the degree of bromination and the molecular weight of both components comprised. In this paper, surface chemical compositions of the cast and the annealing films were investigated by X-ray photoelectron spectroscopy （XPS） and contact angle measurement; meanwhile, surface topographical changes are followed by atomic force microscopy （AFM）. In addition, substantial attention was paid to the effect of annealing on the morphologic variations induced by phase separation and/or dewetting of the thin film. Moreover, the influences of the molecular weight, Mw, as well as the brominated degree, x%, on the sample surface are explored systematically, and the corresponding observations are explained in virtue of the Flory-Huggins theory, along with the dewetting of the polymer thin film.