Influence of annealing on the physical properties of filtered vacuum arc deposited tin oxide thin films

Tin oxide (SnO₂) thin films were deposited on UV fused silica (UVFS) substrates using filtered vacuum arc deposition (FVAD). During deposition, the substrates were at room temperature (RT). As-deposited films were annealed at 400 and 600 °C in Ar for 30 min. The film structure, composition, and surface morphology were determined as function of the annealing temperature using X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The XRD patterns of the SnO₂ thin films deposited on substrates at RT indicated that the films were amorphous, however, after the annealing the film structure became polycrystalline. The grain size of the annealed films, obtained from the XRD analysis, increased with the annealing temperature, and it was in the range 8-34 nm. The AFM analysis of the surface revealed an increase in the film surface average grain size from 15 nm to 46 nm, and the surface roughness from 0.2 to 1.8 nm, as function of the annealing temperature. The average optical transmission of the films in the visible spectrum was >80%, and increased by the annealing ∼10%. The films’ optical constants in the 250-989 nm wavelength range were determined by variable angle spectroscopic ellipsometry (VASE). The refractive indexes of as-deposited and annealed films were in the range 1.83-2.23 and 1.85-2.3, respectively. The extinction coefficients, k(λ), of as-deposited and annealed films were in the range same range ∼0-0.5. The optical energy band gap (E_g), as determined by the dependence of the absorption coefficient on the photon energy at short wavelengths, increased with the annealing temperature from 3.90 to 4.35 eV. The lowest electrical resistivity of the as-deposited tin oxide films was 7.8 × 10⁻³ Ω cm, however, film annealing resulted in highly resistive films.     

X-Ray diffraction study of the evolution of phase and structural state and macroscopic stress during annealing of soft magnetic Fe95 − x Zr5N x films prepared by ion-plasma deposition

The evolution of the phase composition, nanostructure parameters, and macroscopic stress in soft magnetic Fe_{95 ? x} Zr₅N _x films (prepared by ion-plasma deposition onto quartz substrates) during their annealing has been investigated by X-ray diffraction. During deposition, depending on the N content, either a mixed structure composed of an X-ray amorphous phase enriched in Zr and N and a crystalline phase (α-Fe(N) solid solution) or an X-ray amorphous phase enriched in Fe, Zr, and N is formed in the films. During annealing, depending on the temperature and nitrogen content, different combinations of crystalline phases (α-Fe(N) and Zr(N) solid solutions, α-Fe, Fe₄N, Fe₂N, ZrO₂) are formed in the films. The large compressive stress formed in the films during deposition changes to a lower tensile stress during annealing.     

退火温度对Co掺杂CeO2稀磁氧化物薄膜的结构和铁磁性能的影响

采用溶胶-凝胶法,在Si(100)和石英玻璃衬底上制备了3;Co掺杂CeO2稀磁氧化物薄膜,研究了不同退火温度(500 ℃, 600 ℃和700 ℃)对薄膜结构和铁磁性能的影响.XRD 和拉曼光谱结果表明,随着退火温度的升高,薄膜晶化度明显提高.不同退火温度下的3;Co掺杂CeO2薄膜为多晶薄膜,且未破坏CeO2原有的结构.随着退火温度的升高, 晶粒尺寸逐渐增大.另外,3;Co掺杂CeO2薄膜在可见光范围内都有很好的透射率,其室温下的光学带隙Eg随退火温度增加而减小.超导量子干涉磁强计(SQUID)测量表明所有样品都表现出室温铁磁性,随着退火温度的升高,饱和磁化强度和矫顽力增大,700 ℃退火的薄膜具有最大的饱和磁化强度和最大的矫顽力.不同退火温度导致样品的磁性有了明显的变化,这源于磁性产生的不同机理.可见薄膜的结构最终影响了其铁磁性能.     

直流电弧等离子体喷射化学气相沉积高质量金刚石膜残余应力分布的垃曼谱分析

不同工艺条件下在钼衬底(φ60mm)上用100 kW直流电弧等离子体喷射化学气相沉积设备进行金刚石膜的制备.金刚石膜用扫描电镜(SEM)、拉曼谱(激光激发波长为488nm)和X射线衍射来表征.研究结果表明,在直流电弧等离子体喷射化学气相沉积金刚石膜的过程中,内应力大小从金刚石膜的中央到边缘是增加的,并且应力形式是压应力.这说明了在金刚石膜中存在明显的应力不均.甲烷浓度和衬底温度都影响金刚石膜中的内应力.随着甲烷浓度和衬底温度的提高,金刚石膜中的内应力呈增加的趋势.     

An investigation of the magnetic domains in the stressed amorphous FeCoSiB magnetoelastic films

The effects of tensile and compressive stress on the magnetic domains of amorphous FeCoSiB films are investigated. It is observed that the unstressed sample consists of irregular domains while the stressed samples show stripe domains. With the increase of the tensile stress, the stripe domain of the stressed films tends to align parallel to the direction of the stress, while with the increase of the compressive stress the stripe domain of the stressed films tends to align perpendicular to the direction of the stress. The magnetic domain and its evolution under the stress are explained by introducing the magnetoelastic anisotropy induced by the stress.     

Annealing-induced relief of compressive misfit strain in liquid phase epitaxial yttrium iron garnet films

Films of yttrium iron garnet were grown on (111) gadolinium gallium garnet by liquid phase epitaxy from a PbO-B₂O₃ flux. Incorporation of Pb as a substitutional impurity produced an increase in film lattice parameter which resulted in initial compressive misfit strains in the films. The initial strains were relieved by annealing in O₂. The relief process was studied by X-ray double-crystal diffractometry and topography supplemented by optical and scanning electron microscopy. Strain relief was found to be associated with the occurrence of defects which were imaged in both film and substrate topographs. When the initial compressive misfit was sufficiently large, annealing eventually resulted in a tensile strain and the development of cracks which propagated through the films and into the substrates.     

Relations between the optical properties of Cu–Ag:Si3N4 nanocermets and the microstructure of the metallic nanoclusters

Ion beam sputtering has been used to prepare Ag/Cu, Ag and Cu nanoclusters embedded in a Si₃N₄ dielectric matrix with the goal to correlate structural information and optical properties. The optical transmittance spectra of the bimetallic nanoclusters are compared with those obtained in the case of the single metallic nanocermets in the as-deposited state. The influence of a post annealing treatment, at different temperatures, on the optical properties of the bimetallic nanocermets is also discussed. The nanocluster structure has been investigated by X-ray absorption spectroscopy and X-ray diffraction. The chemical composition has been analysed by Rutherford backscattering spectroscopy. The surface plasmon resonance occurring after annealing in a definite temperature range is interpreted as due to the specific atomic arrangement resulting from this treatment.     

Rotary target method to prepare thin films of CdS/SiO2 by pulsed laser deposition

Thin films of CdS-doped SiO₂ glass were prepared by using the conventional pulsed laser deposition (PLD) technique. The laser target consisted of a specially constructed rotary wheel which provided easy control of the exposure-area ratio to expose alternately the two materials to the laser beam. The physical target assembly avoided the potential complications inherent in chemically mixed targets such as in the sol–gel method. Time-of-flight (TOF) spectra confirmed the existence of the SiO₂ and CdS components in the thin-film samples so produced. X-ray diffraction (XRD) and atomic force microscopy(AFM) results showed the different sizes and structures of the as-deposited and annealed films. The wurtzite phase of CdS was found in the 600^oC-annealed sample, while the as-deposited film showed a cubic–hexagonal mixed structure. In the corresponding PL (photoluminescence) spectra, a red shift of the CdS band edge emission was found, which may be a result of the interaction between the CdS nanocrystallite and SiO₂ at their interface.     

基于光谱测试的纯净金刚石品质与缺陷研究

本文利用低温拉曼与光致发光光谱对纯净金刚石晶片的结晶质量、晶体应力分布进行表征分析,并结合电子辐照和快速退火对晶片的杂质缺陷结构开展研究。通过拉曼光谱对金刚石特征峰的表征分析发现,由于金刚石生长机制以及晶片的切割、抛光等因素影响,晶片的边缘与表面应力分布较高。光致发光光谱中的零声子线具有明显的温度依赖性,根据Jahn-Teller效应与电子-声子耦合理论阐明了测试温度变化引起中性单空位缺陷零声子线分裂与红移的机理。对晶片做电子辐照与退火调控处理后,晶片中氮-空位(NV)缺陷显著增多,表明在纯净晶片中氮主要以替代位氮杂质的形式存在。     

High-resolution XRD study of stress-modulated YBCO films with various thicknesses

High-quality epitaxial YBa₂Cu₃O_7−δ (YBCO) superconducting films with thicknesses between 0.2 and 2 μm were fabricated on (0 0 l) LaAlO₃ with direct-current sputtering method. The influence of film thickness on the structure and texture was investigated by X-ray diffraction conventional θ–2θ scan and high-resolution reciprocal space mapping (HR-RSM). The films grew with strictly c-axis epitaxial, and no a-axis-oriented growth was observed up to a thickness of 2 μm. Lattice parameters of the YBCO films with different thicknesses were extracted from symmetry and asymmetry HR-RSMs. The X-ray lattice parameter method was used to determine the residual stress in YBCO films by measuring the a-, b-, c-axis strains, respectively. The results showed that YBCO films within thinner than 1 μm were under compressive stress, which was relieved increasing of film thickness. However, beyond 1 μm in thickness, YBCO films exhibited a tensile stress. Based on the experimental analysis, the variety of residual stresses in the films is mainly attributed to oxygen vacancies with thickness of YBCO film increasing.     

The effect of thermal annealing on the structural and mechanical properties of a-C:H thin films prepared by the CFUBM magnetron sputtering method

a-C:H films were prepared by closed-field unbalanced magnetron (CFUBM) sputtering on silicon substrates using argon (Ar) and acetylene (C₂H₂) gases, and the effects of post-annealing temperature on structural and mechanical properties were investigated. Films were annealed at temperatures ranging from 300 °C to 700 °C in increments of 200 °C using rapid thermal annealing equipment in vacuum ambient. Variations in microstructure were examined using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Surface and mechanical properties were investigated by atomic force microscopy (AFM), nano-indentation, residual stress tester, and nano-scratch tester. We found that the mechanical properties of a-C:H films deteriorated with increased annealing temperature.     

Structural and optical properties of 6CaO·6SrO·7Al2O3 thin films derived by sol-gel dip coating process

The nanostructured 6CaO·6SrO·7Al₂O₃ (C6S6A7) thin films with cubic structure using calcium, strontium metals, aluminium isopropoxide and ethylene glycol monomethyl ether as stating materials has been fabricated via sol-gel route. Based on hydrolysis of Ca²⁺, Sr²⁺ and Al³⁺ in the sol-gel processing using ethylene glycol monomethyl ether as solvent have been employed as the precursor material. The films were coated on soda lime float glass by the dip coating technique and annealed at 450 °C in air atmosphere. The structure, morphology and composition of the films were investigated by Fourier transformed infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy indicating that the films were composed of C6S6A7 nanoparticles with cubic structure. The spectral transmittance of the films was measured in the wavelength range of 200-1100 nm using an UV-visible spectrometer. It has been found that the optical properties of the films significantly affected by precursor chemistry and annealing temperature due to the improvement of the crystallinity of the films with increasing annealing temperature and became stable when the annealing temperature is higher than 450 °C. The C6S6A7 films annealed at 450 °C had high transparency about 80% in wide visible range.     

Growth of epitaxial TmFeCuO4 thin films by pulsed laser deposition

Epitaxial thin films of TmFeCuO₄ with a two-dimensional triangular lattice structure were successfully grown on yttria-stabilized-zirconia substrates by pulsed laser deposition and ex situ annealing in air. The films as-deposited below 500 °C showed no TmFeCuO₄ phase and the subsequent annealing resulted in the decomposition of film components. On the other hand, as-grown films deposited at 800 °C showed an amorphous nature. Thermal annealing converted the amorphous films into highly (0 0 1)-oriented epitaxial films. The results of scanning electron microscopic analysis suggest that the crystal growth process during thermal annealing is dominated by the regrowth of non-uniformly shaped islands to the distinct uniform islands of hexagonal base.     

氧气氛退火对TiO_2薄膜结构和成分的影响

采用电子束蒸发在硅衬底上制备TiO2薄膜,并在氧气氛下进行退火处理。分别使用X射线衍射仪和椭圆偏振仪分析退火前后以及不同退火温度下薄膜样品的结构、成分和折射率,研究氧气氛下进行退火对薄膜结构、成分和折射率的影响。结果表明:氧气氛下退火能够有效地改善薄膜缺氧的问题,提高TiO2薄膜的质量。     

Annealing effects of highly homogeneous a-Si1−xCx:H

We report the effect of annealing on the properties of amorphous hydrogenated silicon carbide thin films. The samples were deposited onto different substrates by plasma enhanced chemical vapor deposition at temperatures between 300 and 350 °C. The gaseous mixture was formed by silane and methane, at the ‘silane starving plasma regime’, and diluted with hydrogen. Rutherford backscattering and Fourier transform infrared spectrometry were used, respectively, to determine the atomic composition and chemical bonds of the samples. The film’s structure was analyzed by means of X-ray absorption fine structure and X-ray diffraction. For temperatures higher than 600 °C, amorphous silicon carbide films annealed under inert atmosphere (Ar or N₂) clearly changed their structural and compositional properties due to carbon loss and oxidation, caused by the presence of some oxygen in the annealing system. At 1000 °C, crystallization of the films becomes evident but only stoichiometric films deposited on single crystalline Si[1 0 0] substrates presented epitaxial formation of SiC crystals, showing that the crystallization process is substrate dependent. Films annealed in high-vacuum also changed their structural properties for annealing temperatures higher than 600 °C, but no traces of oxidation were observed or variations in their silicon or carbon content. At 1200 °C the stoichiometric films are fully polycrystalline, showing the existence of only a SiC phase. The XANES signal of samples deposited onto different substrates and annealed under high-vacuum also show that crystallization is highly substrate dependent.     

Dopant concentration dependence of structure,optical, and magnetic properties of ZnO:Fe thin films

The effects of Fe-dopant concentration on the structure, optical, and magnetic properties of ZnO thin films were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), optical transmittance, absorption, photoluminescence (PL), and magnetic measurements. XRD spectra indicated that the doping of Fe atoms could not only change the lattice constant of ZnO but also improve the crystalline quality of ZnO thin films. And the Zn (0 0 2) diffraction peak at round 36.34°(2θ) was detected with increasing Fe content for the substitution of the Zn in the ZnO film. The band gap edge shifted toward longer wavelength with increase in Fe doping. Moreover, near band edge emission gradually increased with increase in Fe content (up to about 0.82 wt%), and then abruptly decreased due to the concentration quenching effect. Magnetic measurements confirmed that the ferromagnetic behavior of Fe-doped ZnO was correlated with the dopant concentration.     

Structural and physical properties of cobalt nanocluster composite glasses

Composite systems with metallic nanoparticles embedded in dielectrics present peculiar physical properties which are attractive in several application fields. In the case of transition elements, the magnetic properties of the metal clusters embedded in a dielectric matrix mainly depend on the particle size and structure. In this work, silica films containing cobalt atoms were synthesized by RF magnetron co-sputtering deposition technique, with cobalt concentration of a few atomic percent. X-ray diffraction and transmission electron microscopy showed the presence of hcp cobalt nanoclusters in the as-deposited sample with the highest cobalt concentration. After deposition, thermal treatments were performed to promote cobalt compounds or nanoparticle formation. The thermal treatments were able to change the oxidation state of cobalt atoms, as well as the structure of metallic cobalt nanoclusters (from hcp to fcc), their final size depending on both the preparation parameters and the subsequent annealing atmospheres.     

Phase transitions of bismuth clusters

X-ray diffraction patterns, extended X-ray absorption fine structure, and optical absorption coefficients were measured in order to investigate the size-dependence of structural and optical phase transitions of bismuth clusters. Contrary to the case of 15-nm thick films, peaks due to crystalline Bi were not observed in X-ray diffraction patterns of as-deposited 0.5-nm thick films. Optical absorption coefficients of the 0.5-nm thick films are small compared with those of 100-nm thick films, and an optical gap appears in the 0.5-nm thick films. These results show directly the phase transition of bismuth clusters from semi-metallic nanocrystalline to semiconducting amorphous-like clusters with decreasing size.     

射频溅射功率对Mn-Co-Ni-O薄膜结构与性能的影响

采用射频磁控溅射技术在硅衬底上制备了锰钴镍氧(Mn-Co-Ni-O, MCNO)薄膜并进行了后退火处理。利用X射线衍射、扫描电子显微镜、光学测试仪器等测试手段对晶体结构、表面形貌及光学性能进行表征。分析了不同射频溅射功率(60~100 W)对MCNO薄膜表面微观形貌、晶体结构和光学性能的影响。结果表明,在60~90 W下获得的薄膜表面致密且均匀,但在100 W下获得的MCNO薄膜表面晶粒尺寸显著增大。物相分析表明,采用射频磁控溅射沉积的MCNO薄膜主要为尖晶石结构,溅射功率对薄膜结晶质量和择优取向具有显著影响,在80 W下获得的MCNO薄膜结晶质量最佳。同时,拉曼光谱测试也表明该MCNO薄膜表现出最强的Mn⁴⁺—O对称弯曲振动和最小的压应力。紫外-可见-近红外光谱分析表明,MCNO薄膜的吸光范围主要在可见光-近红外波段,在80~90 W溅射功率下获得的MCNO薄膜在近红外波段表现出更强的吸收峰。射频溅射功率的改变会影响薄膜的厚度和结晶质量,从而对薄膜的光学带隙起到调控作用。光致发光光谱测试不同溅射功率下薄膜的缺陷峰发光强度,且在功率为80 W时沉积的薄膜具有最强紫外发射峰,表明改变溅射功率能够有效改善薄膜缺陷及提高晶体质量。     

Influence of annealing temperature and Au concentration on the electrical properties of multilayered a-Ge/Au films

Multilayered a-Ge/Au was investigated to realize low-temperature formation of poly-Ge films on insulator. Increasing Au layer thicknesses, peak intensity of crystalline Ge–Ge TO mode increased and amorphous Ge–Ge TO mode decreased. When Au composition ratio is high, the samples are crystallized under eutectic temperature. Annealing temperature at 673 K, all samples with Au layer are crystallized. Crystalline Ge has no strain evaluated by X-ray diffraction and Raman scattering spectroscopy. However, the Au is compressed or expanded in the films with various annealing temperature. It is thought that this phenomenon changes depending on the size of the space in the film. The behavior of electrical resistivity is changed at eutectic temperature.