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1.
F. Esaka H. YamamotoH. Udono N. MatsubayashiK. Yamaguchi S. ShamotoM. Magara T. Kimura 《Applied Surface Science》2011,257(7):2950-2954
Chemical state analysis by a combination of X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) using synchrotron radiation is performed for β-FeSi2 single crystals and homoepitaxial β-FeSi2 films. The Si 2p XPS and Fe L-edge XAS spectra imply that the annealing at 1173 K to remove native oxide layers on the crystal induces the formation of FeSi in the surface. The formation of FeSi is also confirmed by Si K-edge XAS analysis. For the homoepitaxial β-FeSi2 films grown on the crystals, the Si K-edge XAS spectra indicate that structurally homogeneous β-FeSi2 films can be grown on the β-FeSi2 single crystals when the substrate temperatures of 973 and 1073 K are applied for molecular beam epitaxy (MBE). Consequently, it is indicated that the combination of XPS and XAS using synchrotron radiation is a useful tool to clarify chemical states of β-FeSi2 single crystals and homoepitaxial β-FeSi2 films, which is important to reveal optimized growth conditions of homoepitaxial films. 相似文献
2.
F. Esaka H. Yamamoto Y. Yamada K. Yamaguchi M. Magara 《Applied Surface Science》2010,256(10):3155-3159
A combination of X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) using synchrotron radiation is applied to clarify surface chemical states of β-FeSi2 films fabricated by an ion-beam sputtering deposition method. The differences in the chemical states of the films fabricated at substrate temperatures of 873, 973 and 1173 K are investigated. For the film fabricated at 873 K, Si 2p XPS spectra indicate the formation of a relatively thicker SiO2 layer. In addition, Fe L-edge XAS spectra exhibit the formation of FeSi2−X by preferential oxidation of Si or the presence of unreacted Fe. The results for the film fabricated at 1173 K imply the existence of FeSi2 with α and ? phases. In contrast, the results for the film fabricated at 973 K indicate the formation of relatively homogeneous β-FeSi2. These imply that the relatively excellent crystal property of the film fabricated at 973 K is due to the formation of homogeneous β-FeSi2. As a conclusion, the combination of XPS and XAS using synchrotron radiation is a powerful tool to elucidate the surface chemical states of thin films. 相似文献
3.
Yoshihito Maeda 《Applied Surface Science》2008,254(19):6242-6247
We have investigated the photoluminescence properties of β-FeSi2 and have subsequently reported many studies on the enhancement of luminescence efficiency. We have further discussed a limit for the luminescence efficiency based on the weak confinement theory of excitons in β-FeSi2 nanocrystals. Moreover, we have reported an application of β-FeSi2 with a high refractive index to photonic crystals. 相似文献
4.
Thermal stability of HfO2/Si(001) films prepared by electron beam evaporation in ultrahigh vacuum using atomic oxygen
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HfO2 films on silicon substrates have been prepared by electron beam evaporation in ultrahigh vacuum using atomic oxygen.Synchrotron radiation photon-electron spectroscopy was used to investigate the thermal stability of HfO2 films under an ultrahigh vacuum environment.At the temperature of 750℃,HfO2 films begin to decompose.After being further annealed at 850℃ for 3 min,HfO2 films decomposes completely,partially to form Hf-silicide and partially to form gaseous HfO.Two chemical reactions are responsible for this decomposition process.A small amount of Hf-silicide,which is formed at the very beginning of growth,may result in the films grown subsequently to be loosened,and thereby leads to a relatively low decomposition temperature. 相似文献
5.
ZrO2 thin films were prepared in electron beam thermal evaporation method. And the deposition rate changed from 1.3 to 6.3 nm/s in our study. X-ray diffractometer and spectrophotometer were employed to characterize the films. X-ray diffraction (XRD) spectra pattern shows that films structure changed from amorphous to polycrystalline with deposition rate increasing. The results indicate that internal stresses of the films are compressive in most case. Thin films deposited in our study are inhomogeneous, and the inhomogeneity is enhanced with the deposition rate increasing. 相似文献
6.
Quick preparation and thermal transport properties of nanostructured β-FeSi2 bulk material
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This paper reports that the nanostructured β-FeSi2 bulk materials are prepared by a new synthesis process by combining melt spinning(MS) and subsequent spark plasma sintering(SPS).It investigates the influence of linear speed of the rolling copper wheel,injection pressure and SPS regime on microstructure and phase composition of the rapidly solidified ribbons after MS and bulk production respectively,and discusses the effects of the microstructure on thermal transport properties.There are two crystalline phases(α-Fe2Si5 and ε-FeSi) in the rapidly solidified ribbons;the crystal grains become smaller when the cooling rate increases(the 20 nm minimum crystal of ε-FeSi is obtained).Having been sintered for 1 min above 1123 K and annealed for 5 min at 923 K,the single-phase nanostructured βFeSi2 bulk materials with 200-500 nm grain size and 98% relative density are obtained.The microstructure of β-FeSi2 has great effect on thermal transport properties.With decreasing sintering temperature,the grain size decreases,the thermal conductivity of β-FeSi2 is reduced remarkably.The thermal conductivity of β-FeSi2 decreases notably(reduced 72% at room temperature) in comparison with the β-FeSi2 prepared by traditional casting method. 相似文献
7.
B.Y. Man S.C. XuC. Yang M. LiuS.Z. Jiang Y.Y. MaC.S. Chen A.H. LiuX.G. Gao C.C. WangB. Hu 《Applied Surface Science》2011,257(15):6321-6325
Single-phase β-FeSi2 films on silicon (1 0 0) were fabricated by pulse laser deposition. The structure and crystal quality of the samples were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The field scanning electron microscopy showed that the film thickness increases with the increasing of the laser fluence. Moreover, atomic force microscopy observations revealed the changes of surface properties with different laser fluence. Based upon all experimental results, it is found that 7 J/cm2 is the most favorable for the formation of β-FeSi2 thin films. 相似文献
8.
Sb-doped β-Ga2O3 crystals were grown using the optical floating zone(OFZ) method.X-ray diffraction data and X-ray rocking curves were obtained,and the results revealed that the Sb-doped single crystals were of high quality.Raman spectra revealed that Sb substituted Ga mainly in the octahedral lattice.The carrier concentration of the Sb-doped single crystals increased from 9.55 × 1016 to 8.10 × 1018 cm-3,the electronic mobility depicted a dec... 相似文献
9.
Production of YBa2Cu3O7−x superconducting thin films by pulsed pseudospark electron beam evaporation
H. P. Schölch P. Fickenscher T. Redel M. Stetter G. Saemann-Ischenko W. Benker W. Hartmann K. Frank J. Christiansen 《Applied Physics A: Materials Science & Processing》1989,48(4):397-400
Thin-film superconducting YBa2Cu3O7–x layers have been produced in a single-step process by pulsed electron beam evaporation from a stoichiometric 1-2-3 target. The films were produced at the 100 surface of SrTiO3 substrates heated to a temperature of approximately 1000 K in a pure oxygen atmosphere of about 10 Pa total pressure. After deposition the films were cooled in situ within 20 minutes to ambient temperature. At present, the films are polycrystalline and show a Tc,zero of 83 K with a transition width of 3–5 K. Critical current densities of 7·104 A/cm2 at 4.2 K and zero magnetic field have been achieved. The pulsed electron beams used in these experiments are produced by a pseudospark discharge; the estimated energy density deposited at the target surface by the electron beam is of the order of 4 J/cm2. 相似文献
10.
V. V. Atuchin V. N. Kruchinin A. V. Kalinkin V. Sh. Aliev S. V. Rykhlitski? V. A. Shvets E. V. Spesivtsev 《Optics and Spectroscopy》2009,106(1):72-77
Optical characteristics of the HfO2 − x
N
x
and TiO2 − x
N
x
films obtained by reactive ion beam sputtering have been investigated by spectral ellipsometry. The chemical composition
of the films was determined using X-ray photoelectron spectroscopy. The nitrogen content in the oxynitride films (determined
by the N2/O2 ratio in the gas mixture during synthesis) reached ≈9 at % for TiO2 − x
N
x
and ≈ 6 at % for HfO2 − x
N
x
. It is found that the dispersion relations n(λ) and k(λ) for the TiO2 − x
N
x
films change from those characteristic of titanium dioxide to those typical of titanium nitride with an increase in the nitrogen
content from 0 to ≈9 at %. The optical parameters of the HfO2 − x
N
x
films depend weakly on the nitrogen content in the range 0–6 at %.
Original Russian Text ? V.V. Atuchin, V.N. Kruchinin, A.V. Kalinkin, V.Sh. Aliev, S.V. Rykhlitskiĭ, V.A. Shvets, E.V. Spesivtsev,
2009, published in Optika i Spektroskopiya, 2009, Vol. 106, No. 1, pp. 77–82. 相似文献
11.
Optical properties of molybdenum oxide thin films deposited by?chemical vapor transport of MoO3(OH)2
Young Jung Lee Young Ik Seo Se-Hoon Kim Dae-Gun Kim Young Do Kim 《Applied Physics A: Materials Science & Processing》2009,97(1):237-241
MoO3 thin films are useful for optical devices due to their electrochromic properties. In this study, deposition of MoO2 thin films was successfully accomplished by chemical vapor transport (CVT) of volatile MoO3(OH)2. Subsequently, a MoO3 thin film was obtained by annealing of the deposited MoO2 at 400°C in an O2 atmosphere. As annealing commenced, the optical transmittance of the films increased and their absorbance peaks were broadened
and red-shifted due to reduced oxygen vacancy. Thus, the molybdenum oxide thin films can successfully be deposited using the
CVT technique. 相似文献
12.
X.H. Wang F.B. Zhang K. Saito T. Tanaka M. Nishio Q.X. Guo 《Journal of Physics and Chemistry of Solids》2014
We study the electrical properties and emission mechanisms of Zn-doped β-Ga2O3 film grown by pulsed laser deposition through Hall effect and cathodoluminescence which consist of ultraviolet luminescence (UV), blue luminescence (BL) and green luminescence (GL) bands. The Hall effect measurements indicate that the carrier concentration increases from 7.16×1011 to 6.35×1012 cm−3 with increasing a nominal Zn content from 3 to 7 at%. The UV band at 272 nm is not attributed to Zn dopants and ascribed as radiative electron transition from conduction band to a self-trapped hole while the BL band is attributable to defect level related to Zn dopant. The BL band has two emission peaks at 415 and 455 nm, which are ascribed to the radiative electron transition from oxygen vacancy (VO) to valence band and recombination of a donor–acceptor pair (DAP) between VO donor and Zn on Ga site (ZnGa) acceptor, respectively. The GL band is attributed to the phonon replicas’ emission of the DAP. The acceptor level of ZnGa is estimated to be 0.26 eV above the valence band maximum. The transmittance and absorption spectra prove that the Zn-doped β-Ga2O3 film is a dominantly direct bandgap material. The results of Hall and cathodoluminescence measurements imply that the Zn dopant in β-Ga2O3 film will form an acceptor ZnGa to produce p-type conductivity. 相似文献
13.
The optical properties of monolayer Ge2Sb2Te5 thin films with three different thicknesses prepared by dc magnetron sputtering method at the range of 400-800 nm were studied. The optical absorption coefficients and the optical energy gap (Eg) were calculated, The results gave values for the absorption coefficients in the range of (1.3-7.5)×105 cm-1 which were in the high absorption wavelength region of 相似文献
14.
A. J. G. Schellingerhout R. H. M. van de Leur D. Schalkoord D. van der Marel J. E. Mooij 《Zeitschrift für Physik B Condensed Matter》1988,71(1):1-5
We have analyzed the structure and properties of Y1Ba2Cu3O7–y films on (012) sapphire substrates. The films were obtained by evaporation of the metals in a UHV system with an oxygen beam directed at the substrate. Analysis was performed by X-ray diffraction and electron probe microanalysis [EPMA], after annealing in addition by scanning electron microscopy [SEM] and Auger electron spectroscopy. Without annealing no superconductivity was obtained although sufficient oxygen could be incorporated during growth. The copper does not oxidize. After annealing in oxygen superconductivity is found with an onset temperature of 80–90 K and zero resistance at 30–40 K. A grain-like pattern of 3–5 m typical size is seen. Chemical reactions between layer and substrate are observed. 相似文献
15.
β-FeSi2 thin films were prepared on FZ n-Si (1 1 1) substrates by pulsed laser deposition (PLD). The structural properties and crystallographic orientation of the films were investigated by X-ray diffraction (XRD) analysis. This indicates that β-FeSi2/Si (2 0 2/2 2 0) and the single-crystalline β-FeSi2 can be prepared using PLD. In photoluminescence (PL) measurements at 8 K detected by Ge detector, the PL spectra of the samples annealed at 900 °C for 1, 5, 8 and 20 h showed that the PL intensity of the A-band peak increased depending on annealing time in comparison with those of as-deposited samples. The intrinsic PL intensity of the A-band peak at 0.808 eV of the β-FeSi2 from the 20-h-annealed sample was investigated for the first time by the PLD method detected by an InGaAs detector. This result has been confirmed by temperature dependence and excitation power density of the 20-h-annealed sample with the comparison of other defect-related band peaks of the sample. Cross-sectional scanning electron microscopy (SEM) observation was also performed and the thickness of the thin films was found to be at 75 nm for 20-h-annealed. The thermal diffusion for the epitaxial growth of β−FeSi2/Si was observed when the compositional ratio of Fe to Si was around Fe:Si=1:2 for 20-h-annealed carried out by energy dispersive X-ray spectroscopy (EDX). We discussed high crystal quality of the epitaxial growth and optical characterization of β-FeSi2 achieved after annealing at 900 °C for 20 h. 相似文献
16.
Diamond-like carbon (DLC)–MoS2 composite thin films were synthesized using a biased target ion beam deposition (BTIBD) technique in which MoS2 was produced by sputtering a MoS2 target using Ar ion beams while DLC was deposited by ion beam deposition with CH4 gas as carbon source. The structure and properties of the synthesized films were characterized by X-ray diffraction, X-ray absorption near edge structure (XANES), Raman spectroscopy, nanoindentation, ball-on-disk testing, and corrosion testing. The effect of MoS2 target bias voltage, ranging from −200 to −800 V, on the structure and properties of the DLC–MoS2 films was further investigated. The results showed that the hardness decreases from 9.1 GPa to 7 GPa, the Young?s modulus decreases from 100 GPa to 78 GPa, the coefficient of friction (COF) increases from 0.02 to 0.17, and the specific wear rate coefficient (k) increases from 5×10−7 to 5×10−6 mm3 N−1 m−1, with increasing the biasing voltage from 200 V to 800 V. Also, the corrosion resistance of the DLC–MoS2 films decreased with the raise of biasing voltage. Comparing with the pure DLC and pure MoS2 films, the DLC–MoS2 films deposited at low biasing voltages showed better tribological properties including lower COF and k in ambient air environment. 相似文献
17.
Q. Su 《Applied Surface Science》2009,255(7):4177-4179
β-V2O5 films were successfully prepared on silicon substrates by direct current (DC) reactive magnetron sputtering. X-ray diffraction (XRD), Raman spectra and field emission scan electron spectroscopy (SEM) were used to characterize the samples. Results revealed that the deposition temperature significantly influenced on the crystal structure of V2O5 films in the growth process. When the deposition temperature was below 500 °C, the sputtered film exhibited the α-V2O5 structure. However, β-V2O5 film was successfully obtained at 550 °C. High deposition temperature might provide V and O ions high mobility and energy in the reactive sputtering process, which induced the metastable β-V2O5 phase formed. The thermal stability of β-V2O5 film was studied by micro-Raman spectroscopy. The structure of sputtered β-V2O5 film was unstable under high temperature conditions (beyond 500 °C). 相似文献
18.
Hirotaka Ogawa Akinori Kan Norihiro Ikeda Akihiro Fujita 《Physica B: Condensed Matter》2012,407(21):4308-4312
The effect of In doping on the electroluminescence (EL) properties of Zn2SiO4:In thin films was investigated. In-doped Zn2SiO4 thin films were deposited on BaTiO3 substrates and their EL properties were characterized in this study. X-ray powder diffraction patterns of In-doped Zn2SiO4 powders revealed a single phase of Zn2SiO4 for In concentrations up to approximately 1.5 mol%, whereas a secondary phase of In2O3 was observed for In concentrations in the range of 2–10 mol%. The maximum luminance of thin film electroluminescent (TFEL) devices varied significantly with the amount of In doping. The highest luminance with blue emission was obtained when 2 mol% In was doped. The blue emission of In-doped Zn2SiO4 thin film may be related to the In substitution for Zn. The 2 mol% In-doped Zn2SiO4 thin film exhibited blue emission with CIE color coordinates of x=0.208 and y=0.086. 相似文献
19.
Transparent nano composite PVA–TiO2 and PMMA–TiO2 thin films were prepared by an easy and cost effective dip coating method. Al/PVA–TiO2/Al and Al/PMMA–TiO2/Al sandwich structures were prepared to study the dielectric behavior. The presence of metal–oxide (Ti–O) bond in the prepared films was confirmed by Fourier transform infrared spectroscopy. X-ray diffraction pattern indicated that the prepared films were predominantly amorphous in nature. Scanning electron micrographs showed cluster of TiO2 nanoparticles distributed over the film surface and also there were no cracks and pin holes on the surface. The transmittance of the films was above 80% in the visible region and the optical band gap was estimated to be about 3.77 eV and 3.78 eV respectively for PVA–TiO2 and PMMA–TiO2 films by using Tauc's plot. The determined refractive index (n) values were between 1.6 and 2.3. High value of dielectric constant (?′ = 24.6 and ?′ = 26.8) was obtained for the prepared composite films. The conduction in the composite films was found to be due to electrons. The observed amorphous structure, good optical properties and dielectric behavior of the prepared nano composite thin films indicated that these films could be used in opto-electronic devices and in thin film transistors. 相似文献
20.
This paper reports that/3-Ga2O3 nanorods have been synthesized by ammoniating Ga2O3 films on a V middle layer deposited on Si(111) substrates. The synthesized nanorods were confirmed as monoclinic Ga2O3 by x-ray diffraction,Fourier transform infrared spectra. Scanning electron microscopy and transmission electron microscopy reveal that the grown β-Ga2O3 nanorods have a smooth and clean surface with diameters ranging from 100 nm to 200 nm and lengths typically up to 2μm. High resolution TEM and selected-area electron diffraction shows that the nanorods are pure monoclinic Ga2O3 single crystal. The photoluminescence spectrum indicates that the Ga2O3 nanorods have a good emission property. The growth mechanism is discussed briefly. 相似文献