Papers by Keyword: Raman Spectroscopy

Abstract: Surface with nanometer accuracy is required to manufacturing process of integrated circuit (IC) devices. One of the most promising techniques for surface planarization is chemical mechanical polishing (CMP). CMP is a high efficiency process, both due to the varied chemical and physical properties of the surface materials. Conventional CMP uses the slurry, which is composed of abrasive particles suspended in a chemical solution. The abrasive particle is effective for surface planarization by a chemical mechanism with little mechanical abrasion. So chemical reactivity appears to be an essential factor of CMP process. In our conventional study, fullerenols have been proposed as suitable abrasives for copper CMP. The chemical reactivity of fullerenol is suggested by the fact that high removal rate (150 nm/min) and surface flatness (0.6 nm RMS) have been confirmed using fullerenol slurry. In this study, we analyzed the chemical reactivity between fullerenol molecule and copper surface, which is important to understand the material removal mechanism. Using the intrinsic Raman spectroscopic signal of interaction between fullerenol and copper with surface plasmon resonance (SPR), the chemical reactivity over a period of the reaction process was analyzed. Raman spectroscopy is commonly used in chemical analysis, since vibrational information is specific to the chemical bonds and symmetry of molecules. Therefore, it provides a fingerprint by which the molecule can be identified. However, spontaneous Raman spectroscopic signal is typically very weak, and as a result the main difficulty of Raman spectroscopy is separating the weak inelastically scattered light from the intense Rayleigh scattered laser light. Then Raman spectroscopic signal in this study is further enhanced by the SPR, also known as surface enhanced Raman scattering (SERS). The increase in intensity of the Raman spectroscopic signal for adsorbates on copper surface occurs because of an enhancement in the electric field provided by the surface. This technique enables high-sensitive analysis in the near-surface region. The signature of copper-oxygen bond was measured by Raman spectroscopy for fullerenol/copper system by in-process SERS analysis. It is thought to be caused by the hydroxyls of fullerenol molecule adsorbed on the copper surface. This result suggests that fullerenol molecules absorbing onto the copper surface affect the high efficient material removal.

Abstract: The presence of residual stresses in thermal oxide layers has been recognized for a long time. In the present work, the mechanical fields for chromia oxide are determined either by XRD or Raman spectroscopy. In addition, the microstructure of the chromia films is investigated ant its influence on the evolution of the stress release processes is analyzed.

Abstract: In this paper the wear performance between Partially Stabilized Zirconia (PSZ) plate and silicon nitride ball under dry conditions was investigaed. The wear durability of PSZ with shot peening was higher than that of PSZ without shot peening in the sliding wear test under low Hertzian contact pressure. By shot peening, the transformation from tetragonal to monocryclinic phase with compressive residual stress occurred locally on the PSZ surface. Due to this transformation, the wear durability on the surface of the PSZ plate was improved.

Abstract: . The micro-Raman technique is used to examine the phase purity of Sr₂FeMoO₆ compound in this work. It is found that the Raman spectra of Sr₂FeMoO₆ compound without impurity consists of the peaks at about 440cm^-1 and 620cm^-1. The broad peak and shoulder at 820-890cm^-1 in the Raman spectra is assigned to the most common impurity SrMoO₄ and some other unidentified co-existing phases, which is approved by the results of X-ray diffraction.

Abstract: The effects of charged hydrogen in iron on surface properties of iron in pure water and sodium sulfate solutions of various concentrations were investigsted by open circuit potential monitoring, surface morphology observations, Raman spectroscopy and XRD measurements. Hydrogen in iron shifed the open circuit potential in the negative directions. Hydrogen could change the types of oxide film on iron. Effects of hydrogen on corrosion of iron was More significant in pure water and dilute sodium solutions than those in concentrated solutions.

Abstract: In this work, synthesis strategy of Cu₂O nanosphere and cube was elucidated and the structural, optical and magnetic properties were studied. Cu₂O nanospheres and cubes were synthesized by wet chemical method through selecting the appropriate amount of isopropyl alcohol (IPA) with distilled water as solvent. 5% of IPA yielded cubic shape Cu₂O and 30% of IPA yielded spherical Cu₂O. The phase purity was confirmed with powder XRD. The FTIR result exhibit Cu (I)-O vibrational band around 628 cm^-1 supports the XRD results. In Raman spectra weak band at 508 cm^-1 corresponds to Raman allowed mode. The IR active bands at 110 and 150 cm^-1 are observed because of the violation of selection rules which demonstrates the defects present in synthesized Cu₂O. Raman peaks at 218 and 415 cm^-1 are assigned to multiphonon Raman scattering. The UV-Vis diffuse reflectance spectrum was recorded to calculate the band gap value. The band gap value calculated using Kubelka-Munk equation was 2.015 eV and 2.025 eV, respectively, for Cu₂O cube and nanosphere.

Abstract: In this paper, membranes of 3C-SiC with dimensions up to 10 mm x 15 mm² have been fabricated in epitaxial 3C-SiC/ Si wafers by the means of photolithography, reactive ion etching of 3C-SiC and wet etching of Si. Scanning electron microscope (SEM) micrographs were used to observe the structure of the membrane and the wall formed by the Si wet etching. The quality of the 3C-SiC membranes were observed using Raman Spectroscopy. The remains of <111> Si substrate which was unetched during the Si wet etching were presented with the formation of microstructure defects which showed distinct peaks in comparison to the high quality 3C-SiC membranes at different position. Here, the effect of the membrane fabrication procedures to the 3C-SiC membrane properties especially the morphological structure and its Raman characteristics is discussed in detail.

Abstract: In this paper, we present a modification Raman spectroscopic method-Spatially Offset Raman Spectrosocpy (SORS) for the noninvasive detection for the complex mixed soultion through diffusely scattering and fluorescing bottles and other packaging (including transparent, colored, diffusely cattering palstic and glass beverage, medicine and cosmetic bottles). Compared with conbentional Raman spectroscopic method, SORS is able to effectively supress fluorescence and Raman contributions originating from the container. This inherent ability cans substantially enhance the sensitivity. The application is demonstrated on the noninvasive detedtion of complex mixed solution. The experiments were performed using a 1064nm laser with 500mW average power, and a circular array of collection fibers were surround with the exciting laser. The resluts show that the SORS technology was capable of identifying the presence of concealed complex mixed solution in both transparent and non-transparen samples in quality control and authentication of chemical products.

Abstract: Microstructure evolution of cellulose-based carbon fibers during the heat-treatment process of pyrolysis and carbonization was studied by Raman spectroscopy. The characteristic peaks of cellulose fibers were weakened after a dry process at 100°C and absolutely disappeared after the pyrolysis temperature reached 150°C. For intermediates obtained in the temperature of 150-1300°C, two characteristic Raman peaks appeared at ~1360cm^-1 and ~1580cm^-1, meaning a transition state structure of carbon hexagonal plane started to form. Parameters including I_D1’/I_G’, I_D2’/I_G’ and I_D3’/I_G’ of the intermediates treated in the temperature of 150-1300°C were compared. All the parameters firstly decreased with the increasing heat treatment temperature until a maximum at ~400°C,and then the parameters decreased until the structure turned into a carbon fiber structure at 1300°C.

Abstract: Morphology of thin film poly (3-hexylthiophene) (P3HT) embedded with nanosphere-and nanorod-shape Zinc Oxide (ZnO) has been studied. We deposited the materials on quartz substrate using spin coating technique. The morphology of P3HT: ZnO thin films were investigated using Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray emission spectroscopy (EDX) and RAMAN Spectroscopy and compared. Based on size and shape of both ZnO, it can be seen that nanospheres in P3HT was found to be better than ZnO nanorods in P3HT.