共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Basillais C. Boulmer-Leborgne J. Mathias N. Laidani A. Laurent J. Perrière 《Applied Physics A: Materials Science & Processing》2000,71(6):619-625
We have studied the growth of Al nitride films by laser ablation in order to check the potential of the method. The influence
of process parameters such as nature of the target, laser energy density, nitrogen partial pressure, etc. on the composition,
chemical nature and structure of the films has been investigated. Rutherford backscattering spectrometry, nuclear reaction
analysis, X-ray diffraction and X-ray photoelectron spectroscopy were used to characterize the films. Literature reports on
AlN film growth by laser ablation but oxygen contamination is poorly discussed whereas it is the main problem encountered.
The origin of this contamination and the mechanisms of incorporation were studied, and the crucial parameter was found to
be the residual pressure during ablation. Due to the difference in chemical reactivity between oxygen and nitrogen atomic
species, to obtain pure AlN films it is necessary to increase the concentration of atomic nitrogen. Thus, a RF discharge device
was added allowing a better nitrogen molecule dissociation. Finally, despite composition deviations, the AlN phase can be
formed in the laser-deposited films. Highly textured films presenting epitaxial relationships with crystalline Al2O3 substrates can be grown even with a 10% oxygen concentration.
Received: 7 October 1999 / Accepted: 17 April 2000 / Published online: 13 September 2000 相似文献
2.
J. Sun J.D. Wu Z.F. Ying W. Shi Z.Y. Zhou K.L. Wang X.M. Ding F.M. Li 《Applied Physics A: Materials Science & Processing》2001,73(1):91-95
Combination of pulsed laser ablation with electron cyclotron resonance microwave discharge was demonstrated for a novel method
for low-temperature thin film growth. Aluminum nitride thin films were synthesized on silicon substrates at temperatures below
80 °C by means of reactive pulsed laser deposition in nitrogen plasma generated from the electron cyclotron resonance discharge.
The synthesized films show a very smooth surface and were found to have a stoichiometric AlN composition. X-ray photoelectron
spectroscopy analysis evidenced the formation of aluminum nitride compound. Fourier transform infrared spectroscopy revealed
the characteristic phonon modes of AlN. The AlN films were observed to be highly transparent in the visible and near-IR regions
and have a sharp absorption edge near 190 nm. The band gap of the synthesized AlN films was determined to be 5.7 eV. The mechanisms
responsible for the low-temperature film synthesis are also discussed in the paper. The nitrogen plasma facilitates the nitride
formation and enhances the film growth.
Received: 17 March 2000 / Accepted: 28 March 2000 / Published online: 23 May 2001 相似文献
3.
During thermal treatment, a series of chemical reactions took place in the CrN interlayer in the NiCrAlY/CrN/DSM11 system. The CrN phase in the interlayer was first transformed to intermediate AlN and Cr2N phases during vacuum heat treatment, and thereafter both changed to TiN phase after thermal exposure. The formation of TiN is beneficial to the suppression of elemental interdiffusion. With the good barrier ability and strong interfacial bonding, the CrN interlayer acts as an excellent diffusion barrier. 相似文献
4.
C. Cibert F. Ttard P. Djemia C. Champeaux A. Catherinot D. Ttard 《Superlattices and Microstructures》2004,36(4-6):409
AlN thin films have been deposited on Si(100) substrates by a pulsed laser deposition method. The deposition parameters (pressure, temperature, purity of target) play an important role in the mechanical and physicochemical properties. The films have been characterized using X-ray diffraction, atomic force microscopy, Brillouin light scattering, Fourier transform infrared spectroscopy and wettability testing. With a high purity target of AlN and a temperature deposition of 750 C, the measured Rayleigh wave velocity is close to the one previously determined for AlN films grown at high temperature by metal–organic chemical vapour deposition. Growth of nanocrystalline AlN at low temperature and of AlN film with good crystallinity for samples deposited at higher temperature is confirmed by infrared spectroscopy, as it was by atomic force microscopy, in agreement with X-ray diffraction results. A high hydrophobicity has been measured with zero polar contribution for the surface energy. These results confirm that films made by pulsed laser deposition of pure AlN at relatively low temperature have good prospects for microelectromechanical systems applications. 相似文献
5.
In this work a novel method for synthesising TiN coatings is reported. A high-power diode laser at different powers and traverse speeds was applied to a mild steel substrate, coated with a slurry of titania sol-gel, urea and graphite. The reaction chemical thermodynamics was investigated to estimate the compositions, temperature range, and the required reaction enthalpy for producing TiN. A one-dimensional heat transfer model was used to optimise the processing parameters. Surface morphology and microstructure of the deposited coatings and substrate surface layers were examined using optical microscopy, scanning electron microscope, and field emission gun scanning electron microscope which reveals deposition of very thin layer about 0.3 μm of pure TiN and the presence of sub-micron crystalline structure of TiN forming a metal matrix composite inter-layer with the substrate below the film which suggest a good metallurgically bonding with the substrate. Chemical composition was determined by energy dispersive X-ray analysis. The phases were identified by X-ray diffraction which confirms the synthesis of TiN film for all the samples. Results of nano-hardness measurements revealed a hardness value of the order of 22-27 GPa. 相似文献
6.
In the present paper, porous refractory ceramics synthesized by selective laser sintering/melting from a mixture of zirconium dioxide, aluminum and/or alumina powders are subjected to optical metallography and X-ray analysis to study their microstructure and phase composition depending on the laser processing parameters. It is shown that high-speed laser sintering in air yields ceramics with dense structure and a uniform distribution of the stabilizing phases. The obtained ceramic-matrix composites may be used as thermal and electrical insulators and wear resistant coating in solid oxide fuel cells, crucibles, heating elements, medical tools. The possibility to reinforce refractory ceramics by laser synthesis is shown on the example of tetragonal dioxide of zirconium with hardened micro-inclusion of Al2O3. By applying finely dispersed Y2O3 powder inclusions, the type of the ceramic structure is significantly changed. 相似文献
7.
Nanometer scale Al/AlN multilayers have been prepared by dc magnetron sputtering technique with a columnar target. A set of Al/AlN multilayers with the Al layer thickness of 2.9 nm and the AlN layer thickness variation from 1.13 to 6.81 nm were determined. Low angle X-ray diffraction (LAXRD) was used to analyze the layered structure of multilayers. The phase structure of the coatings was investigated with grazing angle XRD (GAXRD). Mechanical properties of these multilayers were thoroughly studied using a nanoindentation and ball-on-disk micro-tribometer. It was found that the multilayer hardness and reduced modulus showed no strong dependence on the AlN layer thickness. Al2.9 nm/AlN1.13 nm multilayer had more excellent tribological properties than single layers and other proportion multilayers with a lowest friction coefficient of 0.15. And the tribological properties of all the multilayers are superior to the AlN single layer. 相似文献
8.
T.V. Kononenko S.V. Garnov S.M. Pimenov V.I. Konov V. Romano B. Borsos H.P. Weber 《Applied Physics A: Materials Science & Processing》2000,71(6):627-631
Laser ablation of thin TiN films deposited on steel substrates has been studied under wide-range variation of irradiation
conditions (pulsewidth, wavelength, energy density and spot size). It has been demonstrated that both picosecond (150–300 ps)
and nanosecond (5–9 ns) laser pulses were suitable for controllable ablation and microstructuring of a 1-μm-thick TiN film
unlike longer 150-ns pulses. The ablation rate was found to be practically independent of the wavelength (270–1078 nm) and
pulsewidth (150 ps–9 ns), but it increased substantially when the size of a laser spot was reduced from 15–60 μm to 3 μm.
The laser ablation technique was applied to produce microstructures in the thin TiN films consisting of microcraters with
a typical size of 3–5 μm in diameter and depth less than 1 μm. Tests of lubricated sliding of the laser-structured TiN films
against a steel ball showed that the durability of lubricated sliding increased by 25% as compared to that of the original
TiN film.
Received: 28 July 1999 / Accepted: 17 April 2000 / Published online: 20 September 2000 相似文献
9.
Y.W. Goh Y.F. Lu Z.M. Ren T.C. Chong 《Applied Physics A: Materials Science & Processing》2003,77(3-4):433-439
Aluminium nitride (AlN) thin films have been grown on Si(100), Si(111) and Sapphire Al2O3(001) substrates by pulsed KrF excimer laser (wavelength 248 nm, duration 30 ns) ablation of an AlN target with the assistance of nitrogen-ion-beam bombardment. The influence of process parameters such as substrate temperature and ion-beam energy has been investigated in order to obtain high-quality AlN films. The AlN films deposited by pulsed-laser deposition (PLD) have been characterized by X-ray diffraction (XRD) to determine the crystalline quality, grain size and growth orientation with respect to the substrate. The XRD spectra of AlN films on Si(100), Si(111) and Sapphire substrates yield full-width-half-maximum (FWHM) values of approximately 1.6. The bonding characteristics in the films have been evaluated by Raman spectroscopy. The chemical composition of the films has been characterized by X-ray photoelectron spectroscopy (XPS). The surface morphology of the films has been measured by atomic force microscopy (AFM). At a substrate temperature of at least 600 °C, polycrystalline AlN films with orientations of AlN(100) and AlN(101) have been synthesized. PACS 68.55.-a; 81.15.Fg; 77.84.Bw 相似文献
10.
C.M. Rouleau S. Kang D.H. Lowndes 《Applied Physics A: Materials Science & Processing》1999,69(7):S441-S445
GaN/TiN heterostructures were deposited on 4° miscut Si(111) substrates by pulsed KrF laser ablation of TiN through vacuum, followed by reactive pulsed KrF laser ablation of liquid Ga through 70-75 mTorr of microwave-activated NH3. Deposition temperatures of 950 °C and 1050 °C were employed for the TiN layer while 900 °C was employed for the GaN layer. The targets were positioned 5 cm from the substrate and ablated by using a reimaging beamline at a nominal energy density of 3-4 J/cm2. X-ray diffraction (XRD) revealed a highly textured heterostructure with GaN(0001)//TiN(111)//Si(111) and with a rocking curve width for both GaN(0001) and TiN(111) equal to ~1.1°. The mosaic spread through the TiN(001) reflection was ~1.3°, whereas that of the GaN(101_1) was undetectable because of low S/N. Scanning electron microscopy revealed large oriented 10 7m-sized hexagonal crystallites decorating large depressions in the TiN film with many smaller pits also present. The effect of substrate processing and TiN film processing on pit formation was explored. 相似文献
11.
H. Amini Mashhadi G. Kennedy S. Tanaka K. Hokamoto 《Physica B: Condensed Matter》2011,406(6-7):1211-1221
To determine the effect of aluminum content on the formation of in-situ TiN in the Al–Ti–AlN system, a mixture of aluminum, titanium and aluminum nitride powders was subjected to high energy milling. Al content of the mixture was changed according to the following stoichiometric reaction: Ti+AlN+XAl→TiN+(1+X)Al. The value of X was varied from 5.35 to 19.65 based on the stoichiometric calculation of the molar mass of each component expected to result in aluminum matrix composite with TiN weights of 30%, 20% and 10%, respectively, in addition to reaction corresponding to X=0(Ti+AlN→TiN+Al). Thermodynamic factors determine that the amount of Al in the mixture plays a key role in the formation of in-situ TiN. XRD and EPMA results showed that at lower Al content (X=0, 5.35), reaction proceed through a gradual mode. By increasing Al content (X=19.65), no mechanochemical reaction occurred between Ti and AlN. Continuation of the milling process allowed acquisition of in-situ TiN in the designed compositions of AlN–TiN, Al–Ti–AlN–30%TiN, and to some extent, of Al–Ti–AlN–20%TiN. A nanocrystalline solid solution evolved by mechanical alloying (MA) was sustained for prolonged milling time. The mean TiN crystallite size obtained was 10 nm for the AlN–TiN composition. The end product milled powder after 40 h of milling time, equating to the Al–Ti–AlN–30%TiN composition was consolidated into bulk compact using the underwater shock compaction method. The milled specimens were characterized by XRD, scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and microhardness testing. The sample had a uniform and fine-grained composite structure with 99% theoretical density and average microhardness of 434 HV0.1. The results confirmed the possibility of fabricating reliable bulk nanostructured materials by imposing shock compaction on submicron sized powders. 相似文献
12.
E. Sicard C. Boulmer-Leborgne C. Andreazza-Vignolle M. Frainais 《Applied Physics A: Materials Science & Processing》2001,73(1):55-60
The excimer laser nitriding process reported is developed to enhance the mechanical and chemical properties of aluminum alloys.
An excimer laser beam is focused onto the alloy surface in a cell containing 1-bar nitrogen gas. A vapor plasma expands from
the surface and a shock wave dissociates and ionizes nitrogen. It is assumed that nitrogen from plasma in contact with the
surface penetrates to some depth. Thus it is necessary to work with a sufficient laser fluence to create the plasma, but this
fluence must be limited to prevent laser-induced surface roughness. The nitrogen-concentration profiles are determined from
Rutherford backscattering spectroscopy and scanning electron microscopy coupled to energy-dispersive X-ray analysis. Crystalline
quality is evidenced by an X-ray diffraction technique. Transmission electron microscopy gives the in-depth microstructure.
Fretting coefficient measurements exhibit a lowering for some experimental conditions. The polycrystalline nitride layer obtained
is several micrometers thick and composed of a pure AlN (columnar microstructure) top layer (200–500 nm thick) standing on
an AlN (grains) in alloy diffusion layer. From the heat conduction equation calculation it is shown that a 308-nm laser wavelength
would be better to increase the nitride thickness, as it corresponds to a weaker reflectance R value for aluminum.
Received: 17 October 2000 / Accepted: 19 October 2000 / Published online: 23 May 2001 相似文献
13.
采用等离子增强原子层沉积技术在单晶硅基体上成功制备了AlN晶态薄膜, 利用椭圆偏振仪、原子力显微镜、小角掠射X射线衍射仪、高分辨透射电子显微镜、 X射线光电子能谱仪对样品的生长速率、表面形貌、晶体结构、薄膜成分进行了表征和分析, 结果表明, 采用等离子增强原子层沉积制备AlN晶态薄膜的最低温度为200 ℃, 薄膜表面平整光滑, 具有六方纤锌矿结构与(100)择优取向, Al2p与N1S的特征峰分别为74.1 eV与397.0 eV, 薄膜中Al元素与N元素以Al-N键相结合, 且成分均匀性良好.
关键词:
氮化铝
等离子增强原子层沉积
低温生长
晶态薄膜 相似文献
14.
A 2.3 kJ Mather type pulsed plasma focus device was used for the synthesis of a TiN/a-Si3N4 thin film at room temperature. The film was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The XRD pattern confirms the growth of polycrystalline TiN thin film. The XPS results indicate that the synthesized film is non-stoichiometric and contains titanium nitride, silicon nitride, and a phase of silicon oxy-nitride. The SEM and AFM results reveal that the surface of the synthesized film is quite smooth with 0.59 nm roughness (root-mean-square). 相似文献
15.
N. Yasumaru K. Miyazaki J. Kiuchi 《Applied Physics A: Materials Science & Processing》2003,76(6):983-985
We report observation of nanostructures formed on thin TiN and DLC films that were irradiated by 800- and 267-nm, femtosecond
(fs) Ti:sapphire laser pulses at an energy fluence slightly above the ablation threshold. On the ablated thin-film surfaces,
the linearly polarized fs pulses produce arrays of fine periodic structures that are almost oriented to the direction perpendicular
to the laser polarization, while the circularly polarized light forms fine-dot structures. The size of these surface structures
is 1/10–1/5 of the laser wavelength and decreases with a decrease in the laser wavelength.
Received: 3 September 2002 / Accepted: 4 September 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +81-778/62-3306, E-mail: yasuma@fukui-nct.ac.jp 相似文献
16.
M. Yorozu J. Yang Y. Okada T. Yanagida F. Sakai K. Takasago S. Ito A. Endo 《Applied physics. B, Lasers and optics》2002,74(4-5):327-331
A short-pulse X-ray-generation experiment was performed by Compton scattering through interaction between a 3-ps electron
beam and 100-fs laser photons in a 90° scattering configuration. The observed X-ray intensity was typically 3×104 photons/pulse and roughly matched the theoretically expected intensity. The X-ray energy and pulse duration were estimated
theoretically to be 2.3 keV and 280 fs from the observed electron- and laser-beam parameters. The fluctuation of the X-ray
output was measured as 25% (rms) during a 30-min operation. The fluctuation was expressed as a function of the fluctuation
of the timing between the electron and laser beams. The measured fluctuation of the X-rays was approximately consistent with
that caused by the fluctuation of the timing between the beams.
Received: 19 November 2001 / Revised version: 23 January 2002 / Published online: 14 March 2002 相似文献
17.
Manufacturing of fine-structured 3D porous filter elements by selective laser melting 总被引:2,自引:0,他引:2
Selective laser melting (SLM) allows manufacturing porous 3D parts with customized near-net shape and internal geometry designed at the stage of their computer modeling. The relations between laser operational parameters, computer design of the manufacturing object, composition and microstructure of the obtained fine porous structures are discussed. A series of experiments are carried out on PHENIX PM-100 machine to analyze the influence of the manufacturing strategy on anisotropy and regularity of the internal structure of samples from stainless steel, nickel alloys and metal-polymer powders. The issues of accurate reproduction of the parts geometry, strategy of manufacturing thin-walled 3D filters and filters with customized pattern of the micron-sized channels are addressed. Effect of the porous structure on the material filtering performance is analyzed in order to optimize and diversify design of the porous materials for a given application and to improve their operational behavior. 相似文献
18.
19.
CO$lt;sub$gt;2$lt;/sub$gt;激光烧结合成负热膨胀材料Sc$lt;sub$gt;2$lt;/sub$gt;($lt;i$gt;M$lt;/i$gt;O$lt;sub$gt;4$lt;/sub$gt;)$lt;sub$gt;3$lt;/sub$gt;($lt;i$gt;M$lt;/i$gt;=W,Mo)及其拉曼光谱 下载免费PDF全文
用CO2激光烧结合成了负热膨胀材料Sc2(WO4)3和Sc2(MoO4)3. 实验表明, 激光合成负热膨胀材料Sc2(WO4)3和Sc2(MoO4)3属于快速合成技术, 合成一个样品的时间仅需几秒到十几秒, 具有快速凝固的特征; X射线衍射和拉曼光谱分析表明, 所合成的材料为正交相结构, 且具有较高的纯度; 变温拉曼光谱分析表明, 所合成的材料在室温以上没有相变, 但可能有微弱的吸水性; 在对Sc2O3, MoO3, WO3, Sc2(MoO4)3和Sc2(WO4)3拉曼光谱分析的基础上, 给出了激光光子能量及原料和合成产物的声子能级图, 分析了激光烧结合成的机理. 激光光子能量转化为激发声子的能量是光热转化的主要通道, 原料在熔池中反应并快速凝固形成最终产物.
关键词:
负热膨胀材料
合成
激光烧结
拉曼光谱 相似文献
20.
We have grown group III nitride epitaxial films on various substrates by pulsed laser deposition and investigated structural properties of the surfaces and the hetero-interfaces using grazing incidence angle X-ray reflectivity (GIXR) and atomic force microscopy (AFM). It has been found that hetero-interfaces between PLD AlN and conventional substrates such as Al2O3 and Si are quite abrupt (about 0.5 nm) probably due to a less reactive growth ambience. However, we observed a thin interfacial layer (less than 10 nm) at the hetero-interface between AlN and (Mn,Zn)Fe2O4. The surface roughness of AlN is mainly determined by the extent of the lattice mismatch. It has been also found that the roughness at the hetero-interface between GaN and AlN formed by PLD coincides with the surface roughness of the AlN layer. 相似文献