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1.
Two different multilayer structures composed of ten alternating Ni and Al thin films were sputter deposited on Si (111) substrates. These multilayers with individual Ni and Al thin film thicknesses of about 25 nm and 38 nm and of 25 nm and 13 nm, respectively, have the average compositions of Ni0.50Al0.50 and Ni0.75Al0.25. The samples were heat treated in a differential scanning calorimeter instrument with a constant heating rate of 40 °C min −1 in Ar from room temperature to 550 °C. The compositions of as-deposited and heat-treated samples were studied with high-resolution Auger electron spectroscopy (AES) rotational depth profiling. X-ray photoelectron spectroscopy (XPS) analyses show an excess of Ni in both annealed samples. X-ray diffraction measurements of annealed multilayers show the formation of Ni2Al3 and NiAl3 phases in the Ni0.50Al0.50 sample and the presence of Ni3Al and Ni A13 phases with some excess of Ni in the Ni0.75Al0.75 sample. AES and XPS investigations of the reacted layers after 15 min annealing in air at 500 °C disclose considerably different surface oxide thin films: on the Ni0.50Al0.50 layer the oxide thin film consists of Al2O3 with a small amount of NiO, whereas that on the top of the Ni0.75Al0.25 layer is thicker and consists of NiO on top and some Al2O3 below.  相似文献   

2.
Partial transient liquid-phase bonding (PTLP bonding) of silicon nitride (Si3N4) ceramic has been performed using Ti/Ni multi-interlayer in vacuum at 1273–1423 K. Interfacial microstructures were examined by scanning electron microscope, electron probe micro-analysis, and X-ray diffraction. The joint strength has been measured by four-point bending tests from room temperature up to 1000 °C. Interfacial structure of Si3N4/TiN/Ti5Si3 + Ti5Si4 + Ni3Si/(NiTi)/Ni3Ti/Ni is formed after bonding process. The NiTi layer is gradually consumed with simultaneous growth of the reaction layer and the Ni3Ti layer. The room temperature joint strength is significantly affected by the reaction layer thickness, whereas the elevated temperature joint strength significantly depends on whether the low melting point NiTi layer exists in the joint. The joint strength of more than 100 MPa is retained up to 800 °C as the NiTi layer is completely consumed. A model is proposed to optimize the PTLP bonding parameters for optimizing joint strength at both room temperature and elevated temperature.  相似文献   

3.
The crystallization of thin silicon nitride (Si3N4) films deposited on polycrystalline SiC substrates was investigated by X-ray diffractometry as a function of annealing time. The amorphous Si3N4 films were produced by means of reactive r.f. magnetron sputtering. Annealing at temperatures between 1300 and 1700 °C led to the formation of crystalline films composed of -Si3N4 and β-Si3N4. The fraction of β-Si3N4 in the films reaches approximately 40% at temperatures above 1550 °C. Both polymorphic modifications were formed simultaneously during the crystallization process. A transformation of -Si3N4 to β-Si3N4 could not be observed in the time and temperature range investigated. The crystallization process of amorphous Si3N4 can be described according to the Johnson–Mehl–Avrami–Kolmogorov (JMAK) formalism, assuming a three-dimensional, interface controlled grain growth from pre-existing nuclei. The rate constants show an Arrhenius behaviour with an activation enthalpy of approximately 5.5 eV.  相似文献   

4.
The crystallographic texture and the grain size have been measured by X-ray diffraction techniques for about 200 nm-thick Cu films sputter-deposited on amorphous Ta35Si18N47 and Ti33Si23N44 underlayers, and for comparison also on TiN underlayers and oxidized silicon, all on Si (100) substrates. The (111) texture of the as-deposited Cu films increases in the sequence TiN233Si23N4435Si18N47. Amorphous Ta35Si18N47 and Ti33Si23N44 layers evidently promote quite effectively the growth of highly (111) textured Cu films. After vacuum annealing at 450°C for 30 min the texture of Cu rises on Ti33Si23N44, falls on Ta35Si18N47, while that on TiN and on SiO2 changes little and the sequence becomes TiN235Si18N4733Si23N44. The grain size of the as-deposited Cu films increases in the sequence Ti33Si23N44235Si18N4747N53 and rises moderately upon annealing, least for TiN and most for SiO2 and Ti33Si23N44.  相似文献   

5.
We have investigated the stress behaviors and a mechanism of void formation in TiSix films during annealing. TiSix thin films were prepared by DC magnetron sputtering using a TiSi2.1 target in the substrate temperature range of 200–500 °C. The as-deposited TiSix films at low substrate temperature (<300 °C) have an amorphous structure with low stress of 1×108 dynes/cm2. When the substrate temperature increases to 500 °C, the as-deposited TiSix film has a mixture of C49 and C54 TiSi2 phase with stress of 8×109 dynes/cm2. No void was observed in the as-deposited TiSix film. Amorphous TiSix film transforms to C54 TiSi2 phase with a random orientation of (311) and (040) after annealing at 750 °C. The C49 and C54 TiSi2 mixture phase transforms to (040) preferred C54 TiSi2 phase after annealing over 650 °C. By increasing substrate temperature, the transformation temperature for C54 TiSi2 can be reduced, resulting in relieved stress of TiSi2 film. The easy nucleation of the C54 phase was attributed to an avoidance of amorphous TiSix phase. We found that amorphous TiSix→C54 TiSi2 transformation caused higher tensile stress of 2×1010 dynes/cm2, resulting in more voids in the films, than C49→C54 transformation. It was observed that void formation was increased with thermal treatment. The high tensile stress caused by volume decreases in the silicide must be relieved to retard voids and cracks during C54 TiSi2 formation.  相似文献   

6.
The alloy Hastelloy B undergoes phase transformations in the temperature range of 600°–800° C. These phase transformations were studied in some detail by electron microscopy. The essential result of this study was the observed formation of the DO22 structure as an intermediate phase. The DO22 structure is relatively stable in Hastelloy B and its further transformations are easily observable. At 600°C it is transformed to Ni4 Mo followed by a partial transformation to Ni3 Mo, whereas at 700°C Ni3 Mo is formed from DO22 directly.  相似文献   

7.
采用脉冲激光沉积法制备了斜方相Sc2W3O12薄膜。利用X射线衍射仪(XRD)和场发射扫描电镜(FESEM)对Sc2W3O12靶材和Sc2W3O12薄膜组分、表面形貌和靶材断面形貌进行表征, 研究衬底温度与氧分压对薄膜制备的影响。采用变温XRD和热机械分析仪(TMA)分析了Sc2W3O12陶瓷靶材和薄膜的负热膨胀特性。实验结果表明: 经1000℃烧结6 h得到结构致密的斜方相Sc2W3O12陶瓷靶材, 其在室温到600℃的温度范围内平均热膨胀系数为-5.28×10-6 K-1。在室温到500℃衬底温度范围内脉冲激光沉积制备的Sc2W3O12薄膜均为非晶态, 随着衬底温度的升高, 薄膜表面光滑程度提高; 随着沉积氧压强增大, 表面平整性变差。非晶膜经1000℃退火处理7 min后得到斜方相Sc2W3O12多晶薄膜, 在室温到600℃温度区间内, Sc2W3O12薄膜的平均热膨胀系数为-7.17×10-6 K-1。  相似文献   

8.
The intermetallic phase NiAl is a perspective material for high-temperature and shape memory effect applications. Formation of Ni5Al3, Ni2Al, Ni3Al phases which influence the extent of martensitic transformation in NiAl have been studied up to now with controversial results. We have investigated (using SEM and local elemental analyses) the microstructure of nickel enriched surface layers on a Al-79 wt.% Ni alloy. The layers were prepared by diffusion annealing and subsequently given two different heat treatments: at 930°C outside the Ni5Al3 region and at 500°C within the Ni5Al3 region of the phase diagram. In the specimen which was only diffusion annealed separate islands of Ni5Al3 phase elongated in the direction of the concentration gradient could be recognized within the nickel enriched surface layer. In the samples additionally annealed at 500°C, a well defined continuous layer of the Ni5Al3 phase situated 0.4 mm below the specimen surface was found. In the samples annealed at 930°C, isolated Ni3Al precipitates were observed. Their number and size gradually increased with increasing nickel content.  相似文献   

9.
Interactions of Ni0.60Nb0.40 amorphous alloys with polycrystalline overlayers of gold and copper and single-crystal substrates of silicon. GaAs and GaP were observed with Auger depth profiling. The Ni-Nb layer was deposited by r.f. sputtering and was approximately 5000 Å thick. The overlayers were evaporated to a thickness of 1000 Å. The amorphous metal reacted with the gold overlayers and the GaAs and GaP substrates at temperatures well below the nominal crystallization temperature of 650 °C. The Cu/Ni-Nb/Si system, in contrast, was stable at 600 °C for at least 1 h. Samples were also measured that had been contaminated with approximately 5–10 at.% O. Complete separation of the niobium and nickel into distinct layers was seen. For the samples on silicon substrates this separation was accompanied by the formation of a nickel silicide layer.  相似文献   

10.
Cobalt-coated single-crystal Si-Ge layers grown epitaxially by ultrahigh vacuum chemical vapor deposition on silicon substrates were annealed by rapid thermal annealing in the temperature range from 450 °C to 800 °C for periods ranging from 1 to 3 min. The measured sheet resistivities of the films exhibit strong dependence on the annealing conditions. The Co-SiGe film annealed at 700 °C for 3 min had the lowest sheet resistivity (3Ω/p). Structural studies using cross-sectional transmission electron microscopy showed that the cobalt films reacted with the SiGe layer and the thickness of the resulting film increases with increasing annealing temperature or time. Electron diffraction and X-ray microanalysis using energy-dispersive spectrometry showed that CoSi2 was formed during initial annealing. The detection of germanium in the reacted layer and the deviation of the reacted layer's lattice constant from that of CoSi2 indicated that germanium diffused into the CoSi2 and formed ternary compounds (CoxSiyGez) during further annealing.  相似文献   

11.
The metal-induced crystallization (MIC) of hydrogenated sputtered amorphous silicon (a-Si:H) using aluminum has been investigated using X-ray diffraction (XRD) and scanning Auger microanalysis (SAM). Hydrogenated, as well as non-hydrogenated, amorphous silicon (a-Si) films were sputtered on glass substrates, then capped with a thin layer of Al. Following the depositions, the samples were annealed in the temperature range 200 °C to 400 °C for varying periods of time. Crystallization of the samples was confirmed by XRD. Non-hydrogenated films started to crystallize at 350 °C. On the other hand, crystallization of the samples with the highest hydrogen (H2) content initiated at 225 °C. Thus, the crystallization temperature is affected by the H2 content of the a-Si. Material structure following annealing was confirmed by SAM. In this paper, a comprehensive model for MIC of a-Si is developed based on these experimental results.  相似文献   

12.
Amita Verma  Anshu Goyal  R.K. Sharma   《Thin solid films》2008,516(15):4925-4933
The properties of sol–gel derived CeTi2O6 thin films deposited using a solution of cerium chloride heptahydrate and titanium propoxide in ethanol are discussed. The effect of annealing temperature on structural, optical, photoluminescence, photocatalysis and electrochemical characteristics has been examined. Lowest annealing temperature for the formation of crystalline CeTi2O6 phase in these samples is identified as 580 °C. The optical transmittance of the films is observed to be independent of the annealing temperature. The optical energy bandgap of the 600 °C annealed film for indirect transition is influenced by the presence of anatase phase of TiO2 in its structure. Fourier transform infrared spectroscopy investigations have evidenced increased bond strength of the Ti–O–Ti network in the films as a function of annealing temperature. The photoluminescence intensity of the films has shown dependence on the annealing temperature with the films fired at 450 °C exhibiting the maximum photoluminescence activity. The decomposition of methyl orange and eosin (yellow) under UV–visible light irradiation in the presence of crystalline CeTi2O6 films shows the presence of photoactivity in these films. The photocatalytic response of CeTi2O6 films is found to be superior to the TiO2 films. In comparison to crystalline films, the amorphous films have shown superior electrochemical characteristics. The 500 °C annealed amorphous films have exhibited the most appropriate properties for incorporation in electrochromic devices comprising tungsten oxide as the primary electrochromic electrode.  相似文献   

13.
Large grained polycrystalline silicon thin films have been prepared by low-temperature solid phase crystallisation of sputter-deposited hydrogenated amorphous silicon (a-Si:H), with relatively short processing times, and a considerably low thermal budget. Various a-Si:H samples, deposited under different conditions and with varying hydrogen concentrations and hydrogen bonding configurations, were simultaneously annealed. Only a particular set of deposition conditions led to crystallisation. The a-Si:H thin film which was successfully crystallised was prepared in an argon-hydrogen mixture, in which the last few minutes of film deposition occurred in a hydrogen-rich atmosphere. For that film, the hydrogen concentration profile resulted in a much higher hydrogen content on the sample surface than in the bulk, and H-Si bonds were predominantly of the weak type. Crystallisation was accomplished by low-temperature stepwise annealing from 200°C to 600°C at 100°C steps, with samples being cooled down to room-temperature between each annealing step. This resulted in large grained (> 10 μm range) polycrystalline silicon after the 600°C annealing step for a 1.1 μm thick sample. Fourier transform infrared (FTIR) spectroscopy, elastic recoil detection analysis (ERDA) and scanning electron microscopy (SEM) techniques were used to analyse samples before and after crystallisation.  相似文献   

14.
P.C. Joshi  S.B. Desu 《Thin solid films》1997,300(1-2):289-294
Polycrystalline BaTiO3 thin films having the perovskite structure were successfully produced on platinum coated silicon, bare silicon, and fused quartz substrate by the combination of the metallo-organic solution deposition technique and post-deposition rapid thermal annealing treatment. The films exhibited good structural, electrical, and optical properties. The electrical measurements were conducted on metal-ferroelectric-metal (MFM) and metal-ferroelectric-semiconductor (MFS) capacitors. The typical measured small signal dielectric constant and dissipation factor at a frequency of 100 kHz were 255 and 0.025, respectively, and the remanent polarization and coercive field were 2.2 μC cm−2 and 25 kV cm−1, respectively. The resistivity was found to be in the range 1010–1012 Ω·cm, up to an applied electric field of 100 kV cm−1, for films annealed in the temperature range 550–700 °C. The films deposited on bare silicon substrates exhibited good film/substrate interface characteristics. The films deposited on fused quartz were highly transparent. An optical band gap of 3.5 eV and a refractive index of 2.05 (measured at 550 nm) was obtained for polycrystalline BaTiO3 thin film on fused quartz substrate. The optical dispersion behavior of BaTiO3 thin films was found to fit the Sellmeir dispersion formula well.  相似文献   

15.
Hf(OCH2CH2NMe2)4, [Hf(dmae)4] (dmae=dimethylaminoethoxide) was synthesized and used as a chemical vapor deposition precursor for depositing Hf oxide (HfO2). Hf(dmae)4 is a liquid at room temperature and has a moderate vapor pressure (4.5 Torr at 80 °C). It was found that HfO2 film could be deposited as low as 150 °C with carbon level not detected by X-ray photoelectron spectroscopy. As deposited film was amorphous but when the deposition temperature was raised to 400 °C, X-ray diffraction pattern showed that the film was polycrystalline with weak peak of monoclinic (020). Scanning electron microscope analysis indicated that the grain size was not significantly changed with the increase of the annealing temperature. Capacitance–voltage measurement showed that with the increase of annealing temperature, the effective dielectric constant was increased, but above 900 °C, the effective dielectric constant was decreased due to the formation of interface oxide. For 500 Å thin film, the dielectric constant of HfO2 film annealed at 800 °C was 20.1 and the current–voltage measurements showed that the leakage current density of the HfO2 thin film annealed at 800 °C was 2.2×10−6 A/cm2 at 5 V.  相似文献   

16.
Chang Jung Kim   《Thin solid films》2004,450(2):261-264
Ferroelectric bismuth lanthanum titanate (Bi3.25La0.75Ti3O12; BLT) thin films were deposited on Pt/TiO2/SiO2/Si substrate by chemical solution deposition method. The films were crystallized in the temperature range of 600–700 °C. The spontaneous polarization (Ps) and the switching polarization (2Pr) of BLT film annealed at 700 °C for 30 min were 22.6 μC/cm2 and 29.1 μC/cm2, respectively. Moreover, the BLT capacitor did not show any significant reduction of hysteresis for 90 min at 300 °C in the forming gas atmosphere.  相似文献   

17.
Previous studies have suggested that contamination by carbon of the i-Al62Cu25.5Fe12.5 quasicrystalline phase can cause destabilization of the aperiodic structure. Hence, the possibility of carbon diffusion into AlCuFe quasicrystalline thin films and the possible subsequent degradation of the quasicrystalline structure were investigated at room temperature through to 600 °C. The study shows that a carbon layer deposited on the AlCuFe quasicrystalline thin film did not diffuse into the AlCuFe over the temperature range tested whatever the oxide thickness between carbon and alloy. Moreover, the carbon did not react with any of the alloy elements as has been shown with aluminium in the presence of oxygen. Post-deposition annealing at 600 °C of the amorphous alloy, fabricated by simultaneous electron beam evaporation on an amorphous carbon substrate used for transmission electron microscopy (TEM), also leads to a pure quasicrystalline phase thin film without any carbon diffusion from the substrate.  相似文献   

18.
Highly preferred oriented lead barium titanate (Pb1−x,Bax)TiO3 thin film, with particular emphasis on (Pb0.5,Ba0.5)TiO3, can be obtained by spin-coating on MgO (100) substrate by using the precursor sol, which was synthesized from acetylacetone chelating with titanium isopropoxide and ethylene glycol as a solvent, in the sol-gel process. Film thickness, pyrolysis temperature and heating rate were studied systemically to investigate their influences on the formation of preferred oriented thin films. The highly preferred (001)/(100) oriented thin film could be obtained by the pyrolysis of wet film at 500 °C and annealing at 600 °C at a slow heating rate of 5 °C/min. It is confirmed that the tetragonal perovskite structure of the titanate ceramic decreases with an increase of Ba content in (Pb1−x,Bax)TiO3. The (001)/(100) oriented films were synthesized from all compositions between x = 0.2 and x = 0.8, at a crystallization temperature of 600 °C. In particular, for the Ba content in the range of x = 0.50.6, highly preferred (001)/(100) planes were observed.  相似文献   

19.
Nanocomposites in which fine Fe particles are dispersed in a ceramic aluminum borate AlxByOz matrix were synthesized at ambient temperatures by simultaneous hydrolysis of aluminum butoxide and reduction of Fe2+ with sodium borohydride. The nanocomposites were characterized by X-ray powder diffraction, transmission electron microscopy, SQUID magnetometry, and Mössbauer spectroscopy. The as-prepared samples consist of crystalline Fe particles dispersed in an amorphous aluminum borate matrix, which on annealing in H2 atmosphere at T ≥ 800 °C transforms to crystalline aluminum borate; the crystalline aluminum borate exhibits a needle-like morphology. The as-prepared samples all seem to consist of a mixture of ferromagnetic and superparamagnetic Fe particles. The superparamagnetic fraction vanishes completely on annealing in H2 atmosphere at 900 °C. The magnetic results are supported by Mössbauer spectra recorded at room temperature.  相似文献   

20.
Atomic-layer doping of P in Si epitaxial growth by alternately supplied PH3 and SiH4 was investigated using ultraclean low-pressure chemical vapor deposition. Three atomic layers of P adsorbed on Si(100) are formed by PH3 exposure at a partial pressure of 0.26 Pa at 450°C. By subsequent SiH4 exposure at 220 Pa at 450°C, Si is epitaxially grown on the P-adsorbed surface. Furthermore, by 12-cycles of exposure to PH3 at 300–450°C and SiH4 at 450°C followed by 20-nm thick capping Si deposition, the multi-layer P-doped epitaxial Si films of average P concentrations of 1021 cm−3 are formed. The resistivity of the film is as low as 2.4×10−4 Ω cm. By annealing the sample at 550°C and above, it is found that the resistivity increases and the surface may become rough, which may be due to formation of SiP precipitates at 550°C and above. These results suggest that the epitaxial growth of very low-resistive Si is achieved only at a very low-temperature such as 450°C.  相似文献   

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