Kα Source Research Articles

2M NaCl by XPS using monochromatic Al K α x rays

Cryo-XPS enables the study of many substances that are unsuitable for standard XPS analysis, such as moderately volatile liquids, biological samples, porous materials, and polymeric materials that may outgas significantly under ultrahigh vacuum conditions. In this article, XPS spectra of a 50 μl frozen droplet of 2M sodium chloride solution (NaCl) in Millipore water purified to 18.2 MΩ cm at 25 °C were obtained using an Al Kα (1486.6 eV) source with a quartz (1010) crystal monochromator through first order diffraction and irradiating the sample at 54.7° to the surface normal. The sample was sputter cleaned using a Gas Cluster Ion Source pre-acquisition to remove the minor layer of adventitious carbon contamination on the surface. Spectra of the principal lines include Na 1s, O 1s, and Cl 2p. Spectra of O KLL, Na KLL, Cl 2s, Na 2s, Na 2p, O 2s, and valence band were also acquired.

Elucidating the Mechanism of Self-Healing in Hydrogel-Lead Halide Perovskite Composites for Use in Photovoltaic Devices.

Since the emergence of organometal halide perovskite (OMP) solar cells, there has been growing interest in the benefits of incorporating polymer additives into the perovskite precursor, in terms of both photovoltaic device performance and perovskite stability. In addition, there is interest in the self-healing properties of polymer-incorporated OMPs, but the mechanisms behind these enhanced characteristics are still not fully understood. Here, we study the role of poly(2-hydroxyethyl methacrylate) (pHEMA) in improving the stability of methylammonium lead iodide (MAPI, CH3NH3PbI3) and determine a mechanism for the self-healing of the perovskite-polymer composite following exposure to atmospheres of differing relative humidity, using photoelectron spectroscopy. Varying concentrations of pHEMA (0-10 wt %) are incorporated into a PbI2 precursor solution during the conventional two-step fabrication method for producing MAPI. It is shown that the introduction of pHEMA results in high-quality MAPI films with increased grain size and reduced PbI2 concentration compared with pure MAPI films. Devices based on pHEMA-MAPI composites exhibit an improved photoelectric conversion efficiency of 17.8%, compared with 16.5% for a pure MAPI device. pHEMA-incorporated devices are found to retain 95.4% of the best efficiency after ageing for 1500 h in 35% RH, compared with 68.5% achieved from the pure MAPI device. The thermal and moisture tolerance of the resulting films is investigated using X-ray diffraction, in situ X-ray photoelectron spectroscopy (XPS), and hard XPS (HAXPES). It is found that exposing the pHEMA films to cycles of 70 and 20% relative humidity leads to a reversible degradation, via a self-healing process. Angle-resolved HAXPES depth-profiling using a non-destructive Ga Kα source shows that pHEMA is predominantly present at the surface with an effective thickness of ca. 3 nm. It is shown using XPS that this effective thickness reduces with increasing temperature. It is found that N is trapped in this surface layer of pHEMA, suggesting that N-containing moieties, produced during reaction with water at high humidity, are trapped in the pHEMA film and can be reincorporated into the perovskite when the humidity is reduced. XPS results also show that the inclusion of pHEMA enhances the thermal stability of MAPI under both UHV and 9 mbar water vapor pressure.

Insufficient reporting of x-ray photoelectron spectroscopy instrumental and peak fitting parameters (metadata) in the scientific literature

This study was motivated by earlier observations. It is a systematic examination of the adequacy of reporting of information (metadata) necessary to understand x-ray photoelectron spectroscopy (XPS) data collection and data analysis in the scientific literature. The information for this study was obtained from papers published in three high-quality journals over a six-month period in 2019 and throughout 2021. Each paper was evaluated to determine whether the authors had reported (percentages of the papers properly providing the information are given in parentheses) the spectrometer (66%), fitting software (15%), x-ray source (40%), pass energy (10%), spot size (5%), synthetic peak shapes in fits (10%), backgrounds in fits (10%), whether the XPS data are shown in the main body of the paper or in the supporting information (or both), and whether fitted or unfitted spectra were shown (80% of published spectra are fit). The Shirley background is the most widely used background in XPS peak fitting. The Al Kα source is the most widely used x-ray source for XPS data collection. casaxps is the most widely used fitting program for XPS data analysis. There is good agreement between the results gathered during the two years of our survey. There are some hints the situation may be improving. This study also provides a list of the information/parameters that should be reported when XPS is performed.

Depth profiling of AlN and AlxGa1−xN crystals by XPS using Al Kα and Ag Lα line excitation and Ar ion gas cluster ion source

AlGaN-based heterostructures are promising candidates for the fabrication of ultraviolet light-emitting diodes. The analysis of the atomic composition of the grown epitaxial films is important from a technological point of view, allowing precise control over the wavelength and intensity of the emitted light. In this work, the depth profiling of AlN(0001), AlGaN(0001), and AlGaN quantum dot surfaces grown by molecular beam epitaxy was carried out by using angle-resolved x-ray photoelectron spectroscopy (XPS) combined with Ar gas cluster ion source (GCIS) sputtering. Core level shifts in XPS spectra measured by Al Kα and Ag Lα photon sources were determined. We found that sputtering by Ar1000+ ion clusters with an energy of 10 keV creates disorder on the surface and induces changes in surface atomic composition. As a result, depth profiling with a typical surface-sensitive Al Kα photon source is affected by the damaged layer. The application of a less surface-sensitive Ag Lα photon source with high photon energy could suppress the contribution from the damaged surface layer. Combining GCIS sputtering with Ag Lα line XPS measurements is, therefore, very promising for the quantification of atomic composition in the buried epitaxial layers or heterostructures with thicknesses of several tens of nm.

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Microstructured layered targets for improved laser-induced x-ray backlighters.

We present the usage of two-layer targets with laser-illuminated front-side microstructures for x-ray backlighter applications. The targets consisted of a silicon front layer and copper back side layer. The structured layer was irradiated by the 500-fs PHELIX laser with an intensity above 10^{20}Wcm^{-2}. The total emission and one-dimensional extent of the copper Kα x-ray emission as well as a wide spectral range between 7.9 and 9.0 keV were recorded with an array of crystal spectrometers. The measurements show that the front-side modifications of the silicon in the form of conical microstructures maintain the same peak brightness of the Kα emission as flat copper foils while suppressing the thermal emission background significantly. The observed Kα source sizes can be influenced by tilting the conical microstructures with respect to the laser axis. Overall, the recorded copper Kα photon yields were in the range of 10^{11}sr^{-1}, demonstrating the suitability of these targets for probing applications without subjecting the probed material to additional heating from thermal line emission.

Boosting Efficient Ammonia Synthesis over Atomically Dispersed Co-Based Catalyst via the Modulation of Geometric and Electronic Structures

Boosting Efficient Ammonia Synthesis over Atomically Dispersed Co-Based Catalyst via the Modulation of Geometric and Electronic Structures

Ultrafast structural dynamics using time-resolved x-ray diffraction driven by relativistic laser pulses* *Project supported by the National Key R&D Program of China (Grant No. 2017YFA0403301), Science Challenge Project (Grant No. TZ2018005), the National Natural Science Foundation of China (Grant Nos. 11991073, 11721404, 11805266, 11905289, and 61975229), and Key Program of Chinese Academy of Sciences (Grant Nos. XDA25030400 and XDB17030500).

Based on a femtosecond laser plasma-induced hard x-ray source with a high laser pulse energy (> 100 mJ) at 10 Hz repetition rate, we present a time-resolved x-ray diffraction system on an ultrafast time scale. The laser intensity is at relativistic regime (2 × 1019 W/cm2), which is essential for effectively generating Kα source in high-Z metal material. The produced copper Kα radiation yield reaches to 2.5 × 108 photons/sr/shot. The multilayer mirrors are optimized for monochromatizating and two-dimensional beam shaping of Kα emission. Our experiment exhibits its ability of monitoring the transient structural changes in a thin film SrCoO2.5 crystal. It is demonstrated that this facility is a powerful tool to perform dynamic studies on samples and adaptable to the specific needs for different particular applications with high flexibility.

The Enhancement of Selectivity and Activity for Two-Electron Oxygen Reduction Reaction by Tuned Oxygen Defects on Amorphous Hydroxide Catalysts

Amorphous catalysts, thanks to their unique coordinately unsaturated properties and abundant of defect sites, incline to possess higher activity and selectivity than their crystalline counterparts....

Intensity calibration and sensitivity factors for XPS instruments with monochromatic Ag Lα and Al Kα sources

This paper provides a description of the transmission function of an X‐ray photoelectron spectroscopy (XPS) instrument operating with exchangeable Al Kα (1486.6 eV) and Ag Lα (2984.3 eV) sources. Both sources use the same quartz crystal monochromator and illuminate the same area of the sample. The transmission‐function–corrected data from sputter cleaned gold provides a useful reference material to calibrate other instruments of the same type. Sensitivity factors for Ag Lα and Al Kα are calculated from photoionisation cross sections and electron effective attenuation lengths. These compare well with previous experimental values and data acquired from ionic liquids. The intensity of the Ag Lα source is found to be approximately 50 times lower than the Al Kα source. This, coupled with generally lower photoemission efficiencies, results in noisier data or extended acquisition times. However, there are clear advantages to using the Ag Lα source to analyse certain elements where additional core levels can be accessed and for many technologically important elements where interference from Auger electron peaks can be eliminated. The combination of calibrated data from both sources provides direct and easily interpreted insight into the depth distribution of chemical species. This could be particularly important for topographic samples, where angle resolved experiments are not always helpful. We also demonstrate, using thin coatings of chromium and carbon, that the inelastic background in Ag Lα wide‐scan spectra has a significantly increased information depth compared with Al Kα.

Raman spectroscopy and X-ray photo-spectroscopy analysis of graphite media irradiated at low doses

We explore the utility of controlled low-doses (0.2–100 Gy) of photon irradiation as initiators of structural alteration in carbon-rich materials. To-date our work on carbon has focused on β-, x- and γ-irradiations and the monitoring of radiotherapeutic doses (from a few Gy up to some tens of Gy) on the basis of the thermoluminescence (TL) signal, also via Raman and X-ray photo-spectroscopy (XPS), providing analysis of the dose dependence of single-walled carbon nanotubes (SWCNT). The work has been extended herein to investigate possibilities for analysis of structural alterations in graphite-rich mixtures, use being made of two grades of graphite-rich pencil lead, 8H and 2B, both being in the form produced for mechanical pencils (propelling or clutch pencils). 2B has the greater graphite content (approaching 98 wt %), 8H being a mixture of C, O, Al and Si (with respective weight percentages 39.2, 38.2, 9.8 and 12.8). Working on media pre-annealed at 400 °C, both have subsequently been irradiated to penetrating photon-mediated doses. Raman spectroscopy analysis has been carried out using a 532 nm laser Raman spectrometer, while for samples irradiated to doses from 1 to 40 Gy, XPS spectra were acquired using Al Kα sources (hv ∼1400 eV); carbon KLL Auger peaks were acquired using 50 eV Pass Energy. At these relatively low doses, alterations in order-disorder are clearly observed, defect generation and internal annealing competing as dominating effects across the dose range.

Identification, Characterization, and X-ray Crystallographic Analysis of a Novel Type of Lectin AJLec from the Sea Anemone Anthopleura japonica

A novel galactose-specific lectin, AJLec (18.5 kDa), was isolated from the sea anemone, Anthopleura japonica. AJLec was characterized using the hemagglutination assay, isothermal titration calorimetry (ITC), and glycoconjugate microarray analysis and we found that AJLec has a specificity for galactose monomers and β-linked terminal galactose residues in complex carbohydrates, but not for N-acetylgalactosamine (GalNAc), which is commonly recognized by galactose-binding lectins. The primary structure of AJLec did not show homology with known lectins, and a crystal structural analysis also revealed a unique homodimeric structure. The crystal structure of AJLec complexed with lactose was solved by measuring the sulfur single-wavelength anomalous diffraction (S-SAD) phasing with an in-house Cu Kα source method. This analysis revealed that the galactose residue in lactose was recognized via its O2, O3, and O4 hydroxyl groups and ring oxygen by calcium coordination and two hydrogen bonds with residues in the carbohydrate-binding site, which demonstrated strict specificity for the β-linked terminal galactose in this lectin.

Comparative Analysis of Ni- and Ni0.9Pt0.1-Ge0.9Sn0.1 Solid-State Reaction by Combined Characterizations Methods

GeSn-based alloys present a novel pathway towards the monolithic integration of light sources in mid infrared CMOS-compatible Si photonic circuitry [1]. Semiconductor optoelectronic devices need efficient metallic contacts to receive and deliver power and signal. Ni-stanogermanides (Ni-GeSn) have been proposed as a promising candidate material to reach both low specific contact (Rc) and sheet resistance (Rsh) [2,3] to contact efficiently GeSn-based photonic or electronic devices. However, a low thermal stability of these layers has been evidenced, together with compound agglomeration and segregation [4]. As a solution to these problems Wang et al. showed that the co-sputtering of Ni and Pt extended the thermal stability of the stanogermanides to higher temperatures. Thus leading to a broader window for stanogermanidation and suppressing, to some extent, agglomeration and degradation [4]. In this work, we propose a comparative and comprehensive study of the solid-state reaction of Ni and Ni0.9Pt0.1 films with compressively-strained, 60 nm-thick Ge0.9Sn0.1 layers, epitaxially grown on Ge-buffered Si (100) substrates. Prior to metallization, surface preparation was performed with a 1 min dip in 1% diluted HF sequentially rinsed in deionized water and dried with a N2 gun. Then, 10 nm of Ni or Ni0.9Pt0.1 were deposited by physical vapor deposition and capped with 7 nm of TiN. The Ni and Ni0.9Pt0.1-Ge0.9Sn0.1 phase sequence and crystalline evolution were monitored by in-situ x-ray diffraction (XRD) using an Empyrean PANalytical X-ray diffractometer equipped with a copper (Cu Kα) source, a linear detector (PIXcel1D) and a HTK 1200 Anton Paar furnace working under secondary vacuum. Profiles were acquired from 50 to 600 °C, with 5 °C steps and a scanning time of 7 min per temperature step. The phase analysis was complemented by ex-situ in-plane reciprocal space map with a Rigaku SmartLab X-ray diffractometer. Additionally, samples metallized with the same procedure were ex-situ annealed for 30 s at temperatures ranging from 150 up to 550 °C (with 50 °C steps), in a rapid thermal annealing (RTA) treatment in a N2 environment. The evolution of the surface morphology and the electrical properties were measured by atomic force microscopy (AFM) in Tapping mode with a Bruker FastScan equipment and sheet resistance (Rsh) with a four-point probe meter. AFM and Rsh evidenced that Pt addition improves both morphological and electrical properties of the layers at high temperature. The addition of Pt prevents the surface Root-mean-square (RMS) roughness from increasing with temperature (Figure 1) and postpones morphological surface degradation. Concerning the electrical properties (Figure 2), a plateau where sheet resistance remains stable and low is obtained with Pt addition between 350 and 450 °C. Meanwhile, a sudden increase of Rsh values for Ni-system is observed, this immediately after obtaining the minimum values (9.1 Ω/sq at 350 °C). XRD results for the Ni-Ge0.9Sn0.1 system (Figure 3) reveal a sequential growth in which the first phase appearing corresponds to a Ni-rich phase, i.e. Ni5(Ge0.9Sn0.1)3. Then, at 245 °C, the mono-stanogermanide phase Ni(Ge0.9Sn0.1) is observed; this latter is stable up to 600 °C. The addition of 10 at.% of Pt in Ni thin films (Figure 4) modifies the reaction kinetics, evidenced by the delay in Ni consumption together with a snowplow phenomenon. Additionally, it strongly affects the phase formation sequence promoting PtSnx compound formation and β-Sn segregation as well as a preferential out-of-plane orientation of the mono-stanogermanide phase. Further, the Ni0.9Pt0.1 mono-stanogermanide is unstable and a destabilization of the system is observed to the benefit of the Ni mono-stanogermanide phase, around the 345 – 355 °C temperature range. A summary of the phase formation sequence for both systems is given in Figure 5. The potential impact on device integration of these observations will be discussed. Even though the addition of Pt complicates the solid-state reaction, it was observed that its beneficial impact on surface morphology has an important role for maintaining the integrity of the electrical properties.

Near Surface Structures and the Electronic States of Polar InN

InN has received great research attention because of the small band-gap (~ 0.7 eV) and superior electrical transport properties. As a wurtzite crystal lacks inversion symmetry along c-axis direction, In-polar and N-polar InN exhibit different properties. Therefore, investigation of near-surface structure and electronic states of polar InN films are important to fully realize their potential. Due to the element and chemical state specificity and the larger probing depth, hard X-ray photoelectron diffraction (HXPD) was used to investigate the near-surface structures of polar InN films [1].The HXPD system consists of a monochromatic Cr Kα source (5414.7 eV), a high energy version of the VG SCIENTA R4000 10 kV analyzer with wide acceptance objective lens.The angle acceptance of the combined objective lens and the analyzer is ±35° with an angular resolution of 0.5°. The total energy resolution was 1 eV. In this study, the polar angle θ is defined to be zero for the photoemission direction normal to a sample surface. The θ-dependent sensitivity of the analyzer, was calibrated using an amorphous GeSbTe sample.Figure 1 shows the HXPD patterns from In 3d5/2 and N 1s core levels of In-polar and N-polar InN. The patterns were different from each other and then they were compared with the simulation results using a multiple-scattering cluster model[2], which is shown in Fig.1. It was found that the near-surface structure of the In-polar InN film was close to the ideal wurtzite structure. On the other hand, on the N-polar InN film, defects-rich surface was formed. In addition, the existence of the In-polar domains was observed in the HXPD patterns.

High photon flux Kα Mo x-ray source driven by a multi-terawatt femtosecond laser at 100 Hz.

We develop a pulsed hard x-ray Kα source at 17.4keV produced by the interaction of a multi-terawatt peak power infrared femtosecond laser pulse with a thick molybdenum (Mo) target at a 100Hz repetition rate. We measure the highest Mo Kα photon production reported to date corresponding to a Kα photon flux of 1×1011 ph/(sr·s) and an estimated peak brightness of ∼2.5×1017 ph/(s·mm2·mrad2(0.1% bandwidth)) at ∼5×1018 W/cm2 driving laser intensity.

Low-temperature solution-processed sol-gel K-rich KNN thin films for flexible electronics

ABSTRACTSputtered lead-free piezoelectric materials like potassium sodium niobate (K1-xNaxNbO3 or KNN) have received significant technological interest in recent years in light of several reports of piezoelectric constants comparable to lead zirconium titanate (PZT). Potential applications include self-powered sensors, actuators, and low acoustic impedance transducers. For large area printed applications, it is vital to develop low-temperature solution processed deposition methods. In this work, sol-gel synthesis of K-rich (70:30) KNN was carried out under an argon atmosphere, using acetate precursors, followed by precipitation of white KNN powder upon careful drying. Powder X-ray diffraction (XRD) scans of the product with a Cu Kα source after calcination revealed a dominant (110) peak, accompanied by smaller (100) and (010) peaks, in agreement with published standard KNN data. The composition of K-rich phase was confirmed using energy dispersive X-ray spectroscopy (EDX). To produce thin films, the sol was spin coated on a surface-treated Au-coated Si substrate, followed by slow annealing to obtain low surface roughness films (RMS roughness ﹤∼10 nm) of thickness ∼200 nm after solvent removal. Atomic force microscopy (AFM) scans revealed an unremarkable amorphous film. However, deposition of the sol on the Au-coated backside of Si wafer under similar processing conditions revealed limited polycrystalline film formation observed using optical profilometry. Thin film XRD measurements of the deposited film reveal orthorhombic phase growth of KNN, though the unannealed film was more amorphous than the calcined KNN film. Preliminary piezoresponse force microscopy (PFM) scans were used to estimate a piezoelectric constant (d33) ∼ 2.7 pC/N, consistent with the general expectation of lower piezoelectric constants for thin sol-gel films. The highest processing temperature used at any step during the deposition process was 90°C, consistent with the applications involving flexible polyimide substrates. This low-temperature thin-film growth suggests a potential route towards integration of large area piezoelectric generators for environmentally-friendly autonomous flexible sensor applications, with better control of phase and composition during the solution-phase deposition of KNN.

Experimental and numerical study of ultra-short laser-produced collimated Cu Kα X-ray source

AbstractKα X-ray sources generated from the interaction of ultra-short laser pulses with solids are compact and low-cost source of ultra-short quasi-monochromatic X-rays compared with synchrotron radiation source. Development of collimated ultra-short Kα X-ray source by the interaction of 45 fs Ti:sapphire laser pulse with Cu wire target is presented in this paper. A study of the Kα source with laser parameters such as energy and pulse duration was carried out. The observed Kα X-ray photon flux was ~2.7 × 108 photons/shot at the laser intensity of ~2.8 × 1017 W cm−2. A model was developed to analyze the observed results. The Kα radiation was coupled to a polycapillary collimator to generate a collimated low divergence (0.8 mrad) X-ray beam. Such sources are useful for time-resolved X-ray diffraction and imaging studies.

Temperature dependent structural studies on the spin correlated system A2FeCoO6 (A= Sm, Eu, Dy and Ho) using synchrotron radiation

The temperature dependent structural studies carried out on the spin-correlated system A2FeCoO6 (A= Sm, Eu, Dy and Ho) or AFCO (A= Sm, E, D and H), using synchrotron radiation is presented. Owing to the large absorption cross-sections of the rare earths; Eu, Sm and Dy for neutrons, synchrotron radiation is one of the best available candidates for probing the system. The perovskite phase formation is inferred from laboratory XRD with Cu Kα source. The temperature dependent synchrotron X-ray diffraction (SXRD) experiments show the coexistence of monoclinic P21/n and orthorhombic Pbnm phases in Ho and Dy, while Eu and Sm are formed in single phase Pbnm. The temperature dependent DC magnetization measurements infer the presence of many interesting features such as thermal hysteresis, magnetic irreversibility, spin re-orientation, re-entrant magnetization and negative magnetization.

Utilization of Hard X-Ray Photoelectron Spectroscopy for Silicon-Based Negative Electrodes Buried within Solid Electrolyte Interphase

Silicon is one of the alternative materials for currently used negative electrodes in Li-ion batteries because of its high lithium insertion capability. However, volume expansion of silicon-based active materials accompanied with the lithium insertion is a severe problem towards their practical application since this volume expansion can destroy both the silicon-based material itself and electrical connection composed of binders, current collectors and the silicon-based materials. Hence, understanding of the lithium insertion is essential to design the silicon-based negative electrode with a high tolerance to the volume expansion. However, these negative electrodes are buried with a thin film, so-called, a solid electrolyte interphase (SEI), which often prohibits the characterization of electrode surfaces. X-ray photoelectron spectroscopy (XPS) is a surface-sensitive technique which can analyze the composition and oxidation states of elements within the sample surfaces, and often combined together with destructive ion-sputtering methods to obtain their depth profile. XPS utilizing hard x-rays, so-called HAXPES (Hard X-ray Photoelectron Spectroscopy), can be a complementary non-destructive technique to analyze a deeper region from the surface. Recently, we constructed an in-house HAXPES equipped with a Cr Kα (5415 eV) source for electrode materials buried within the SEI. Here, we compared “destructive” Ar ion sputtering-XPS and “non-destructive” HAXPES to characterize the depth profile of the SEI-covered Si(111) negative electrodes with and without lithium insertion.

Fabrication of MoS2 Thin Film at Low Temperature By Atmospheric-Pressure Solution Based Mist CVD

Recently, layered transitional metal dichalcogenide (TMD) materials which are bound by vdW forces between the layers have received much attention owing to their excellent properties. In this study, we focused on layered molybdenum disulfide (MoS2) thin film fabrication by mist CVD. MoS2 is a semiconductor with a non-zero energy band gap of 1.8 eV which is close to the typical band gap energy of a-Si:H (1.7 eV), contrary to graphene with a zero energy band gap [1]. The fabrication of MoS2 layered thin film by mechanical exfoliation (ME), chemical vapor deposition (CVD), and molecular beam epitaxy (MBE) have been previously studied and reported in literatures. However, there are some problems to be solved for scaling up those processes to industrial level. In ME, size of layered MoS2 thin films are smaller than 1×1 mm2. In CVD and MBE, large amount of energy is consumed by the heater set at 700-1000°C and the vacuum pump keeping the low pressure of 10-5 Pa. [2-5]. Therefore, the development of a new method which is suitable for industrial expansion is very important. Thus, in this study, we demonstrate the fabrication of MoS2 by mist CVD. mist CVD is one of functional thin-film fabrication methods carried out under open-air atmospheric-pressure, which is developed for advanced control of precursor streams in order to achieve the fabrication of uniform thin films.In the experiment, MoS2 was fabricated by a homemade fine-channel type mist CVD system, which was designed to achieve the uniform flow and homogeneous temperature in the reactor, details of which were reported elsewhere [6]. The quartz substrates were used. Prior to the thin-film growth, substrates were cleaned by acetone, isopropanol, and deionized water each for 2 min. Thin films were fabricated by using a precursor solution containing a mixture of (NH4)6Mo7O24・4H2O and thiourea dissolved in methanol. The growth temperature was varied from 200 to 450°C at 25°C intervals. Raman spectra of samples were evaluated using a micro-Raman system with incident laser wavelengths of 532 nm (2.33 eV). The binding states of the samples were investigated by X-ray Photoelectron spectroscopy (XPS) operated at 15 kV and 26.7 mA with the unmonochromated Al Kα source. The crystal structure of the samples was identified by grazing incidence X-ray diffraction (GIXD). In this paper, results of Raman spectroscopy and XPS are shown and discussed.In the results, the slight change of the color on the substrate surfaces of some samples was seen after fabrication of the MoS2 thin film and was seemed that uniform thin films were obtained on 30×30 mm2 square substrate. Raman peaks around 380 cm-1 (E1 2g) and 410 cm-1 (A1g) were observed from the samples prepared at 300 - 450°C, except the samples prepared at temperature lower than 300°C. Raman peaks around 383.0 cm-1 (E1 2g) and 407.8 cm-1 (A1g) in bulk MoS2 are reported in the references [7]. XPS analysis of the samples prepared at 350°C shows binding energies corresponding to Mo3d (229.25, 232.58, and 235.48 eV) and S2p (162.22 and 162.96 eV) levels in Fig.2. According to the literature, binding energy peaks corresponding to Mo-S bonds; Mo3d5/2 (229.25 eV), Mo3d3/2 (232.2 eV), S2p3/2 (162.1 eV), and S2p1/2 (163.1 eV) as well as corresponding to Mo-O bonds; Mo3d5/2 (232.8 eV) and Mo3d3/2 (235.5 eV) has been observed in the case of XPS analysis of bulk MoS2 powders [8]. A small amount of MoO3 is included in MoS2 powder, as evident from low intensity of those binding energy peaks corresponding Mo-O bonds compared with that of Mo-S bonds in this literature. Similar results were obtained in XPS analysis of MoS2 thin film prepared by mist CVD at 350°C. From these results, it is suggested that layered MoS2 thin films with high quality were successfully fabricated by mist CVD. Remarkably, the growth temperature of MoS2thin-films by mist CVD is comparatively lower temperature than that of the traditional CVD. In summary, we have demonstrated the successful fabrication of MoS2 thin-film at atmospheric pressure and relatively low growth temperature by mist CVD. Reference [1] K. Ueno and K. Tsukagoshi, Jpn. J. Appl. Phys., 83 (2014) 274 [2] H. Li, et. al., Acc. Chem. Res., 47 (2014) 1067[3] Yi-H. Lee, et. al., Adv. Mater., 24 (2012) 2320[4] M.R. Laskar, et. al., Appl. Phys. Lett., 102 (2013) 252108 [5] H.F. Liu, et. al., Chem. Vap. Deposition, 21 (2015) 241[6] T. Kawaharamura, Jpn. J. Appl. Phys., 53 (2014) 05FF08[7] H. Li, et. al., Adv. Funct. Mater, 22 (2012) 1385[8] M.A. Baker, et. al., Appl. Surface Sci., 150 (1999) 255