Measurement of residual stress in a multi-layer semiconductor heterostructure by micro-Raman spectroscopy

Si-based multilayer structures are widely used in current microelectronics. During their preparation, some inhomogeneous residual stress is induced, resulting in competition between interface mismatching and surface energy and even leading to structure failure. This work presents a methodological study on the measurement of residual stress in a multi-layer semiconductor heterostructure. Scanning electron microscopy（SEM）, micro-Raman spectroscopy（MRS）, and transmission electron microscopy（TEM） were applied to measure the geometric parameters of the multilayer structure. The relationship between the Raman spectrum and the stress/strain on the [100] and [110] crystal orientations was determined to enable surface and crosssection residual stress analyses, respectively. Based on the Raman mapping results, the distribution of residual stress along the depth of the multi-layer heterostructure was successfully obtained.

中煤级煤Micro-Raman结构对甲烷吸附的响应

煤与甲烷、二氧化碳等流体作用后的体积膨胀及其机制一直是煤层气地质学和煤与瓦斯突出防治研究中的重要课题之一。以往的研究主要集中在宏观吸附膨胀及变形,并从力学的角度解释其膨胀机制。实际上,煤作为由大分子构成的分子体系,与甲烷、二氧化碳的相互作用是一种分子现象,其膨胀变形的本质应该是分子体系发生了变化,因此揭示煤大分子结构对煤体吸附膨胀的响应特征是认识其机制的基础。应用显微-拉曼光谱法对吸附甲烷前后的8个中煤级煤样(镜质组最大反射率R_(o)=1.08%~1.80%)进行了结构表征,并运用Origin 8.5软件对煤样吸附甲烷前后的拉曼光谱曲线进行了分峰拟合,在此基础上计算了煤样吸附前后的拉曼光谱结构参数。结果表明:原煤和吸附煤的G峰与D峰的峰位差d(G-D)随着煤级的增加有增大趋势,G峰半峰宽(FWHM-G)呈减小趋势,表明在反射率1.08%~1.80%阶段,煤结构有序度和微晶尺寸随煤级增加而逐渐增加;大芳香环(≥6)的相对含量(A_(D)/A_(G))出现先增加后减小的趋势,这是以较大芳香环的生成为主转为向石墨结构生成为主的结果;随着煤级增加,原煤的大芳香环结构中“杂质”(A_(S)/A_(D))及氢化芳环上的C—C的含量(A_(S)/A_(total))均有减小的趋势,反映出煤结构中sp^(2)-sp^(3)杂化烷基碳或氢化芳环逐渐减少,有序度逐渐增加;当R_(o)>1.3%时,吸附煤相对原煤的d(G-D)及A_(D)/A_(G)减少,小芳香环相对含量(A_(GR+VR+VL)/A_(D)),A_(S)/A_(D),A_(S)/A_(total)和FWHM-G增加,表明甲烷吸附变形引起环数较大的芳香环和微晶结构破裂形成较小的芳香环。这一结果对于认识煤大分子结构与甲烷的相互作用机制提供了理论依据。

Comparison between Double Crystals X-ray Diffraction and Micro-Raman Measurement on Composition Determination of High Ge Content Si_(1-x)Ge_(x) Layer Epitaxied on Si Substrate

It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.

Development of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus

We developed a set of in-situ Micro-Raman spectroscopy system for autoclave experimental apparatus because of the scientific significance of in-situ Micro-Raman spectroscopy system under the high-pressure hydrothermal condition.We used this system to measure the Raman spectrum of water-fluid and quartz crystal at the temperature ranging from 125 to 420℃.The signal-tonoise ratio of the Raman signal is good.

Low-energy(40 keV) proton irradiation of YBa_2Cu_3O_(7-x) thin films:Micro-Raman characterization and electrical transport properties

To investigate the damage profiles of high-fluence low-energy proton irradiation on superconducting materials and related devices, Raman characterization and electrical transport measurement of 40-keV-proton irradiated YBa_2Cu_3O_(7-x)(YBCO) thin films are carried out. From micro-Raman spectroscopy and x-ray diffraction studies, the main component of proton-radiation-induced defects is found to be the partial transition of superconducting orthorhombic phase to the semiconducting tetragonal phase and non-superconducting secondary phase. The results indicate that the defects induced in the conducting CuO_2 planes, such as increased oxygen vacancies and interstitials, can result in an increase in the resistivity but a decrease in the transition temperature TCwith the increase in the fluence of proton irradiation, which is confirmed in the electrical transport measurements. Especially, zero-resistance temperature TC_0 is not observed at a fluence of 10^(15)p/cm^2.Furthermore, the variation of activation energy U_0 can be explained by the plastic-flux creep theory, which indicates that the plastic deformation and entanglement of vortices in a weakly pinned vortex liquid are caused by disorders of point-like defects. Point-like disorders are demonstrated to be the main contribution to the low-energy proton radiation damage in YBCO thin films. These disorders are likely to cause flux creep by thermally assisted flux flow, which may increase noise and reduce the precision of superconducting devices.

Study of Thermal Conductivity of Porous Silicon Using the Micro-Raman Method

In this work, we are interesting in the measurement of thermal conductivity (on the surface and in-depth) of Porous silicon by the micro-Raman spectroscopy. This direct method (micro-Raman spectroscopy) enabled us to develop a systematic means of investigation of the morphology and the thermal conductivity of Porous silicon oxidized or no. The thermal conductivity is studied according to the parameters of anodization and fraction of silicon oxidized. Thermal transport in the porous silicon layers is limited by its porous nature and the blocking of transport in the silicon skeleton what supports its use in the thermal sensors.

A polarized micro-Raman study of a 0.65PbMg_(1/3)Nb_(2/3)O_3-0.35PbTiO_3 single crystal

Polarized micro-Raman spectra of a 0.65PbMgl/3Nb2/303 0.35PbTiO3 （0.65PMN-0.35PT） single crystal poled in the [001] direction are obtained in a wide frequency range （50 2000 cm^-1） at different temperatures. The best fit to the Raman spectrum at 77 K is achieved using 17 Lorenzians to convolute into it, and this is proved to be a reasonable fit. According to the group theory and selection rules of overtone and combinational modes, apart from the seven Raman modes that are from first-order Raman scattering, the remaining ones are attributed to being from second-order Raman scattering. A comparison between the experimental results and theoretical predictions shows that they are in satisfactory agreement with each other. Our results indicate that at 77 K the sample belongs to the rhombohedral symmetry with the C^53v（R3m） space group （Z = 1）. In our study, on heating, the 0.65PMN 0.35PT single crystal undergoes a rhombohedral → tetragonal → cubic phase transition sequence. The two phase transitions occur at 340 and 440 K, which correspond to the disappearance of the soft mode near 106 cm-1 recorded in VV polarization and the vanishing of the band around 780 cm^-1 in VH polarization, respectively.

Micro-Raman and SEM Analysis of Minerals from the Darhib Mine, Egypt

The Darhib mine is one of the several talc deposits in the Hamata area of southeastern Egypt. Several specimens of minerals coming from this mine were subjected to complementary investigation by micro-Raman spectrometry and scanning electron microscopy. The difficulty in their identification is the appearance of most of them: they are all very small and only visible under the mineral binocular microscope(×10 - ×40). They appear as small crystals in fissures and holes and a visual determination on colour and crystal gives only a guess of what kind of mineral it could be. Therefore, only after analyzing them by micro-Raman and scanning electron microscopy it was possible to identify their structure and they can be divided in three main groups: one is quite generic and several minerals of different species were identified, such as quartz, talc, mottramite and chrysocolla, very common in the talc mine (these ones are Si-based minerals);the other one is constituted by four samples which are Zn and/or Cu rich, which means minerals of the rosasite or aurichalcite groups;the last group is constituted by two samples containing mainly Pb..

Evaluation of self-healing properties of inhibitor loaded nanoclay-based anticorrosive coatings on magnesium alloy AZ91D

This study emphasizes on the evaluation and comparison of the anticorrosive properties of sol-gel coatings with and without inhibitor loaded nanocontainers.In this case,naturally available clay nanotubes(halloysite)were loaded with cationic corrosion inhibitors Ce 3+/Zr 4+.These nanocontainers were dispersed in hybrid organic-inorganic sol-gel matrix sol.Coating was applied on magnesium alloy AZ91D using the sols containing modified and unmodified nanocontainers employing the dip coating method and cured at 130℃for 1 h in air.Corrosion resistance of coated/uncoated substrates were analyzed using electrochemical impedance spectroscopy,potentiodynamic polarization and weight loss measurements after exposure to 3.5 wt%NaCl solution for varying time durations between 24 h to 120 h.Self-healing ability of coatings was evaluated by micro-Raman spectroscopy after 120 h exposure to 3.5 wt%NaCl solution.Coatings generated after dispersion of corrosion inhibitor loaded clay in hybrid sol-gel matrix have shown more promising corrosion resistance when compared to just the sol-gel matrix coatings,after prolonged exposure to corrosive environment.

Residual stress evolution regularity in thermal barrier coatings under thermal shock loading

Residual stress evolution regularity in thermal barrier ceramic coatings （TBCs） under different cycles of thermal shock loading of 1 100℃ was investi- gated by the microscopic digital image correlation （DIC） and micro-Raman spec- troscopy, respectively. The obtained results showed that, as the cycle number of the thermal shock loading increases, the evolution of the residual stress under- goes three distinct stages： a sharp increase, a gradual change, and a reduction. The extension stress near the TBC surface is fast transformed to compressive one through just one thermal cycle. After different thermal shock cycles with peak temperature of 1 100℃, phase transformation in TBC does not happen, whereas the generation, development, evolution of the thermally grown oxide （TGO） layer and micro-cracks are the main reasons causing the evolution regularity of the residual stress.

Sicilian serpentinite xenoliths containing abiotic organics with nanodiamond clusters as key model for prebiotic processes

Rock fragments from the deepest parts of a buried hydrothermal system belonging to the Mesozoic Tethys Ocean entered as xenoliths in a Miocenic diatreme,hence brought to the surface,in the Hyblean Plateau(Sicily).Some xenoliths consist of strongly serpentinized ultramafic rocks bearing blebs of abiotic organic matter,where clusters of amorphous carbon nanoparticles,including nanodiamonds,are immersed.Such an occurrence conjures up established hypotheses that diamond surfaces are suitable catalytic platforms stimulating the assemblage of complex bio-organic molecules relevant to the emergence of life on Earth.The appearance of bio-organic molecules under primitive Earth conditions is one of the major unsolved questions on the origin of life.Here we report new micro-Raman spectra on blebs of abiotic organic matter from a selected xenolith.Diamond bands were related to hydrogenated nanocrystalline diamonds,with size of nearly 1-1.6 nm,formed from organics at low pressures and temperatures.In particular,diamond surfaces can give rise to crystalline interfacial water layers that may have played a fundamental role in the early biosphere evolution as a good medium for rapidly transporting positive charges in the form of hydrated protons.Nowadays,proton gradients in alkaline hydrothermal vents along oceanic ridges are generally viewed as key pre-biotic factors.In general,serpentinites span the entire geological record,including prebiotic times.These hydrous ultramafic rocks often display evidence of abiotic carbon species,both organic and inorganic,including nanodiamonds,being also capable to give rise to chemiosmotic processes and proton gradients necessary to the organisms,such as the"Last Universal Common Ancestor"(LUCA),in the prebiotic Earth.

Quantitative of pesticide residue on the surface of navel orange by confocal microscopy Raman spectrometer

The potential of Confocal micro Raman spectroscopy in the quantitative analysis of pesticide(Chlorpyrifos,Omethoate)residues on orange surface is investigated in this work.Quantitative analysis models were established by partial least squares(PLS)using different preprocessing methods(Smoothing,First derivative,MSC,Baseline)for pesticide residues.For pesticide resi-dues,the higher correlation coefficients(r)is 0.972 and 0.943,the root mean square error of prediction(RMSEP)is 2.05%and 2.36%,respectively.It is therefore clear that Confocal micro-Raman spectroscopy techniques enable rapid,nondestructive and reliable measurements,so Raman spectrometry appears to be a prormising tool for pesticide residues.

Phase transformation and nanograting structure on TiO2 rutile single crystal induced by infrared femtosecond laser

In this paper, TitaiJum dioxide （TiO2） rutile single crystal was irradiated by infrared femtosecond laser pulses with repetition rate of 250 kHz. For a P-polarized femtosecond laser, the periodic nanograting structure on the ablation crater surface was formed . The periodicity is much less than the laser wavelength. The direction of nanograting alignment depends on the polarization laser beam. Micro-Raman spectra show that the intensity of Eg Raman vibrating mode of rutile phase increases and that of Alg Raman vibrating mode decreases apparently within the ablation crater. With the increase of irradiation time and laser average power, the Raman vibrating modes of anatase phase emerged. Rutile phase of TiO2 single crystal is partly transformed into anatase phase.

Tensile Strength and Oxide Analysis of Carbon Steel in Concrete Exposed in Atmospheric Environment for 53 Years

The tensile strength of a corroded rebar in a 53-year-old concrete structure was studied. The microstructure of the metallic substrate, the fracture surface, and the corrosion product layers were investigated. Metallographic observation results showed that the carbon steel was constituted of ferrite and some pearlite. The tensile test results indicated that the corroded rebar presented low strength and elongation. In addition, the fracture surface of the rebar in the tensile test displayed dimple fracture behavior. The Raman spectroscopy results indicated that corrosion products at the general corrosion zone were obviously different from those at the localized corrosion zone. The rust layer at the general corrosion zone was composed of goethite （α-FeOOH）, magnetite （Fe304）, and hematite （α-Fe203）, while that of the pitting zone was made of feroxyhyte （δ-FeOOH）, goethite （α-FeOOH）, and hematite （α-Fe203）. However, the general tendencies that the corrosion products were constituted of a mix of oxides and hydroxides, the oxides mainly existed in the internal part and the hydroxides more presented in the external layer were observed.

Local Drug Delivery Strategy for Cancer Treatment: Use of Biocompatible Sol-Gel-Derived Porous Materials

Porous silica xerogel materials have been developed to use as drug-release agents to be implanted directly in or near cancerous tissues. In order to test the capacity of the materials to absorb and then to release medicinal substances, a battery of examinations (UV and visible micro-Raman, porosity measurements, UV-visible absorption spectra) have been made using test drug molecules (clotrimazole, primaquine diphosphate and the anti-cancer agent vinblastine sulphate). Results show that the molecules can be post-doped into the gels and the Raman data provide indications of the best conditions for detecting the substances absorbed in the gels. Spectroscopic results show that the drug molecules are released by the xerogel over a period of 10 days. These results are promising for the development of these materials as drug-release agents.

The 2-axis stress component decoupling of {100} c-Si by using oblique backscattering micro-Raman spectroscopy

With the application of strain engineering in microelectronics,complex stress states are introduced into advanced semiconductor devices.However,there is still a lack of effective metrology for the decoupling analysis of the complex stress states in semiconductor materials.This paper presents an investigation on the 2-axis stress component decoupling of{100}monocrystalline silicon(c-Si)by using oblique backscattering micro-Raman spectroscopy.A spectral-mechanical model was established,and two practicable methods for actual stress decoupling analyses were proposed.The verification experiments demonstrated the correctness and applicability of the methods proposed in this paper.

Investigation on the laser ablation of SiC ceramics using micro-Raman mapping technique

关于激光脱离行为的研究当在空格和激光的高效的镜子，或激光出现，原文如此，陶艺为他们的反激光能力的改进有大意义微用机器制造的技术作为在微电子的机械系统(MEMS ) 的电子部件。在这个工作，激光脱离原文如此，陶艺被在 1064 nm 使用 12 ns 持续时间的激光脉搏执行了。激光在 0.1 J/cm 2 下面导致了损坏阀值(LIDT ) 被 1-on-1 模式和它的损坏形态学获得出现在与一条清楚的边界烧坑形式。印射技术的 Micro-Raman 首先在激光脱离机制上在我们的学习被介绍原文如此由识别在未受损伤、切除激光的区域之间的物理、化学的变化出现。在脱离过程期间，原文如此，表面主要经历了分解到元素的 Si 和 C，这被结束了，由水晶取向的某转变伴随了。氧化也原文如此发生了但是仅仅在目标区域的边上的小数量，当有时，不与更高的精力密度在中心 SiO 2提示，也许因为在切除区域的 O 2空气的缺乏，由在从 633～779 的 1505 ng 的碳的 SiO 2的消除?作文。Th 蹘 ? 蹘？？

Determination of channel temperature for AlGaN/GaN HEMTs by high spectral resolution micro-Raman spectroscopy

Channel temperature determinations of A1GaN/GaN high electron mobility transistors （HEMTs） by high spectral resolution microRaman spectroscopy are proposed. The temperature dependence of the E2 phonon fre quency of GaN material is calibrated by using a JYT64000 microRaman system. By using the Lorentz fitting method, the measurement uncertainty for the Raman phonon frequency of 40.035 cm1 is achieved, correspond ing to a temperature accuracy of 43.2 ~C for GaN material, which is the highest temperature resolution in the published works. The thermal resistance of the tested A1GaN/GaN HEMT sample is 22.8 °C/W, which is in rea sonably good agreement with a three dimensional heat conduction simulation. The difference among the channel temperatures obtained by microRaman spectroscopy, the pulsed electrical method and the infrared image method are also investigated quantificationally.

Using X-ray computed tomography and micro-Raman spectrometry to measure individual particle surface area, volume, and morphology towards investigating atmospheric heterogeneous reactions

Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogeneous reactions usually have large variations and may not be relevant to real atmospheric conditions. One of the major reasons for this is the use of bulk samples in laboratory experiments, while particles in the atmosphere are suspended individually. A number of technologies have been developed recently to study heterogeneous reactions on the surfaces of individual particles. Precise measurements on the reactive surface area, volume, and morphology of individual particles are necessary for calculating the uptake coefficient, quantifying reactants and products, and understanding the reaction mechanism better. In this study, for the first time we used synchrotron radiation X-ray computed tomography（XCT） and micro-Raman spectrometry to measure individual CaCO_3 particle morphology, with sizes ranging from 3.5–6.5 μm. Particle surface area and volume were calculated using a reconstruction method based on software threedimensional（3-D） rendering. The XCT was first validated with high-resolution fieldemission scanning electron microscopy（FE-SEM） to acquire accurate CaCO_3 particle surface area and volume estimates. Our results showed an average difference of only 6.1% in surface area and 3.2% in volume measured either by micro-Raman spectrometry or X-ray tomography. X-ray tomography and FE-SEM can provide more morphological details of individual Ca CO3 particles than micro-Raman spectrometry. This study demonstrated that X-ray computed tomography and micro-Raman spectrometry can precisely measure the surface area, volume, and morphology of an individual particle.

The evolution of coal, examining the transitions from anthracite to natural graphite: a spectroscopy and optical microscopy evaluation

Coal-derived natural graphite(CDNG)has multiple industrial applications.Here,ten metamorphic coals from anthracite to CDNG were obtained from Lutang and Xinhua in the Hunan Province and Panshi in the Jilin Province.Bulk characterization(proximate and ultimate analyses,X-Ray powder diffraction(XRD),and powder Raman spectroscopy),along with optical microscopy,scanning electron microscope(SEM)and micro-Raman spectroscopy were utilized to examine the transitions from anthracite to semi-graphite to CDNG.The XRD and Raman spectroscopy data indicate that from anthracite to highly ordered graphite the average crystal diameter(La)and height(Lc)increased from 6.1 and 4.6 nm to 34.8 and 27.5 nm,respectively.The crystalline parameters of the CDNG samples from Panshi and Lutang varied slightly when closer to the intrusive body.Optical microscopy and SEM indicated that in the anthracite samples there were thermoplastic vitrinite,devolatilized vitrinite,and some“normal”macerals.In the meta-anthracite,pyrolytic carbon,mosaic structure,and crystalline tar were present.In the CDNG there were flake graphite,crystalline aggregates,and matrix graphite.The crystalline aggregates show the highest structural ordering degree as determined from Raman spectral parameters(full-width at half maxima(G-FWHM)~20 cm^(−1),D1/(D1+D2+G)area ratio(R2)value<0.5).The flake graphite is less ordered with G-FWHM~28 cm^(−1) and 0.5<R2<1,but a larger grain size(up to 50μm).The mosaic structures were likely the precursors of the matrix graphite through in situ solid-state transformation.The pyrolytic carbon and crystalline tars are the transient phase of gas-state and liquid-state transformations.This study is beneficial to realize the rational utilization of CDNG.