- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Determination of nanoscale titanium oxide thin film phase composition using X-ray photoelectron spectroscopy valence band analysis
摘要： The phase compositions of nanoscale thick titania films on the titanium were determined using X-ray photoelectron spectroscopy valence band analysis for the first time, by deconvoluting the two-peak structure of valence band into five peaks and analysing the relative peak area. The titania films of thickness varying from about 2 nm to 8 μm were obtained by the air oxidation of commercially pure titanium at different temperatures. The titania films formed on titanium for oxidizing temperatures up to 200 °C were amorphous, with thickness < 10 nm. The sub-stoichiometric oxides present at the TiO2-Ti interface were composed of Ti3+, Ti2+ and Ti1+ states when the film of thickness was < 10 nm. At 300 °C, when the titania film thickness was < 20 nm, it was fully converted to rutile phase and remained stable up to 1000 °C. A broadening of full-width half-maxima of the core level peaks for the titania layers was attributed to the presence of surface hydroxyl group and stress gradient within the oxide layer. The absence of metastable anatase phase in the titania layers at lower temperatures was attributed to the presence of high stresses within the oxide layers owing to their nanoscale thickness.
关键词： X-ray Photoelectron Spectroscopy,Thin film,Valence band,Surface phase composition,Titania,Titanium
更新于2025-11-21 11:24:58
-
Solar water splitting over Rh <sub/>0.5</sub> Cr <sub/>1.5</sub> O <sub/>3</sub> -loaded AgTaO <sub/>3</sub> of a valence-band-controlled metal oxide photocatalyst
摘要： Improvement of water splitting performance of AgTaO3 (BG 3.4 eV) of a valence-band-controlled photocatalyst was examined. Survey of cocatalysts revealed that a Rh0.5Cr1.5O3 cocatalyst was much more effective than Cr2O3, RuO2, NiO and Pt for water splitting into H2 and O2 in a stoichiometric amount. The optimum loading amount of the Rh0.5Cr1.5O3 cocatalyst was 0.2 wt%. The apparent quantum yield (AQY) at 340 nm of the optimized Rh0.5Cr1.5O3(0.2 wt%)/AgTaO3 photocatalyst reached to about 40%. Rh0.5Cr1.5O3(0.2 wt%)/AgTaO3 gave a solar to hydrogen conversion efficiency (STH) of 0.13% for photocatalytic water splitting under simulated sunlight irradiation. Bubbles of gasses evolved by the solar water splitting were visually observed under atmospheric pressure at room temperature.
关键词： Rh0.5Cr1.5O3 cocatalyst,valence-band-controlled photocatalyst,solar water splitting,apparent quantum yield,AgTaO3,solar to hydrogen conversion efficiency
更新于2025-11-19 16:51:07
-
Infrared Spectroscopy on Electronic Structures of Platinum-group Metal Pernitrides MN2 (M = Ru, Rh, Ir, and Pt)
摘要： The electronic structures of platinum-group metal pernitrides MN2 (M = Ru, Rh, Ir, and Pt) were investigated via synchrotron radiation infrared spectroscopy and first-principles calculations. Measured reflectance spectra of marcasite-type RuN2 and RhN2 showed Drude-like responses, approaching 1 as the photon energy was decreased, whereas reflectance of arsenopyrite-type IrN2 and pyrite-type PtN2 became ~0.3 in the low photon energy region with a few features. These findings agreed well with the predictions of the metallic nature of marcasite-type RuN2 and RhN2 and the semiconducting properties of arsenopyrite-type IrN2 and pyrite-type PtN2, respectively. The measured reflectance spectra were also reasonably consistent with the calculated optical responses. The band gaps of IrN2 and PtN2 were estimated to be 0.8 and 2.1 eV, respectively, via first-principles calculation with a modified Becke–Johnson (MBJ) potential for the exchange potential.
关键词： first-principles calculation,platinum-group metal pernitride,infrared reflectance spectra,valence band electronic structure
更新于2025-09-23 15:22:29
-
Valence band behaviour of zirconium oxide, Photoelectron and Auger spectroscopy study
摘要： In this study X-ray Photoelectron Spectroscopy and Ultraviolet Photoelectron Spectroscopy were combined to investigate the effect of oxygen incorporation on the valence band behaviour of ZrOx. The Auger transitions involving valence bands are found to mimic the self-folded density of state measured using Ultraviolet Photoelectron Spectroscopy. The valence band once constructed in a sub-oxide form, stays at a fixed energy position despite the change in the stoichiometry. This behaviour is found to be useful in setting a reference for X-ray Photoelectron Spectroscopy charge correction. The results of the charged corrected spectra were compared to other methods and found to be in great agreement. Finally, a correlation between the core-level binding energy and the structural property of ZrOx is given.
关键词： valence band,Ultraviolet Photoelectron Spectroscopy,X-ray Photoelectron Spectroscopy,Photoelectron,zirconium oxide,Auger spectroscopy
更新于2025-09-23 15:21:01
-
Interfacial structure of SrZr <sub/><i>x</i> </sub> Ti <sub/>1?</sub><sub/><i>x</i> </sub> O <sub/>3</sub> films on Ge
摘要： The interfacial structure of SrZrxTi1?xO3 films grown on semiconducting Ge substrates is investigated by synchrotron X-ray diffraction and first-principles density functional theory. By systematically tuning the Zr content x, the effects of bonding at the interface and epitaxial strain on the physical structure of the film can be distinguished. The interfacial perovskite layers are found to be polarized as a result of cation-anion ionic displacements perpendicular to the perovskite/semiconductor interface. We find a correlation between the observed buckling and valence band offsets at the SrZrxTi1?xO3/Ge interface. The trends in the theoretical valence band offsets as a function of Zr content for the polar structures are in agreement with reported X-ray photoelectron spectroscopy measurements. These results have important implications for the integration of functional oxide materials with established semiconductor based technologies.
关键词： synchrotron X-ray diffraction,density functional theory,valence band offsets,SrZrxTi1?xO3 films,Ge substrates,interfacial structure
更新于2025-09-23 15:21:01
-
Comparison study of temperature dependent direct/indirect bandgap emissions of Ge1-x-ySixSny and Ge1-ySny grown on Ge buffered Si
摘要： Temperature-dependent photoluminescence (PL) of two sets of ternary samples with fixed tin concentrations of ~5.2% (Ge0.924Si0.024Sn0.052, and Ge0.911Si0.036Sn0.053) and ~7.3% (Ge0.90Si0.027Sn0.073, and Ge0.888Si0.04Sn0.072) were measured along with their binary counterparts (Ge0.948Sn0.052 and Ge0.925Sn0.075). The variations of direct bandgap emission (ED) and indirect bandgap emission (EID) with temperature were studied for both ternary and binary alloys by means of Gaussian curve fitting, and the results are compared. The bandgap widths of ternaries clearly increase after Si incorporation into the GeSn with similar Sn concentrations. It is found that for the ternaries both ED and EID peak energies are blue shifted, and the energy separation of ED and EID peaks becomes larger than that of binaries for similar Sn concentrations. Moreover, both ED and EID peaks appear at room temperature (RT) in the GeSiSn spectra, but the ED peak position is greater than EID, indicating these ternaries are indirect bandgap materials. Low temperature PL validates the existence of indirect PL emission in Ge0.90Si0.027Sn0.073 and direct gap behavior in Ge0.925Sn0.075, indicating GeSn becomes a direct bandgap material at lower Sn concentration than GeSiSn. The PL intensities of these ternaries are generally weaker and the spectra become more complicated than those of binaries, probably due to increased strain and defects in the ternaries. Finally, it is found that the effect of large differences in strain of ternary samples on PL peak positions can be greater than that of small Si composition differences in ternaries. A large compressive strain in ternaries can also make splitting of the ED into ED,HH (conduction band minimum-Γ valley to heavy hole maximum) and ED,LH (conduction band minimum-Γ valley to light hole maximum) transitions more observable in the PL spectra.
关键词： strain,germanium tin,photoluminescence,direct/indirect bandgap emissions,valence band splitting,germanium silicon tin
更新于2025-09-19 17:15:36
-
Highly Crystallized C-Doped Nickel Oxide Nanoparticles for p-Type Dye-Sensitized Solar Cells with Record Open-Circuit Voltage Breaking 0.5 V
摘要： In this work, unique carbon-doped NiO nanostructure (denoted as C/NiO) was synthesized via a facile precipitation/reduction reaction, followed by a subsequent oxidation process. The successful introduction of carbon in NiO gave rise to multiple tailing of the physical and electronic characteristics, including morphology, crystallinity, and conductivity, and valence band edge position. The carbon-doped NiO-fabricated dye sensitized solar cells actively generated an unrivalled VOC of 0.50 V and also a significantly increased short-circuit current densities (JSC, 0.202 mA cm-2), leading to an overall efficiency of 0.053%. The improved of photovoltaic performance could be mainly attributed to the significantly enhanced charge transport property and regarded charge recombination occurred at the NiO/electrolyte interface. This work provides an extremely simple and effective strategy for incorporating nonmetal elements in semiconductor oxides with remarkably improved photovoltaic performance.
关键词： charge transport,carbon-doped NiO,dye-sensitized solar cells,photovoltaic performance,valence band edge
更新于2025-09-12 10:27:22
-
Band alignment of atomic layer deposited SiO <sub/>2</sub> on (010) (Al <sub/>0.14</sub> Ga <sub/>0.86</sub> ) <sub/>2</sub> O <sub/>3</sub>
摘要： The (AlxGa1?x)2O3/Ga2O3 system is attracting attention for heterostructure ?eld effect transistors. An important device design parameter is the choice of gate dielectric on the (AlxGa1?x)2O3 and its band alignment at the heterointerface. The valence band offset at the SiO2/(Al0.14Ga0.86)2O3 heterointerface was measured using x-ray photoelectron spectroscopy. The SiO2 was deposited by atomic layer deposition (ALD) onto single-crystal β-(Al0.14Ga0.86)2O3 grown by molecular beam epitaxy. The bandgap of the SiO2 was determined by re?ection electron energy loss spectroscopy as 8.7 eV, while high resolution XPS data of the O 1s peak and onset of elastic losses were used to establish the (Al0.14Ga0.86)2O3 bandgap as 5.0 eV. The valence band offset was determined to be 1.60 ± 0.40 eV (straddling gap, type I alignment) for ALD SiO2 on β-(Al0.14Ga0.86)2O3. The conduction band offset was 2.1 ± 0.08 eV, providing for a strong electron transport restriction.
关键词： x-ray photoelectron spectroscopy,(Al0.14Ga0.86)2O3,SiO2,atomic layer deposition,conduction band offset,band alignment,valence band offset
更新于2025-09-10 09:29:36
-
Single Crystal Growth and Characterization of the Chalcopyrite Semiconductor CuInTe2 for Photoelectrochemical Solar Fuel Production
摘要： Transition metal chalcogenides are a promising family of materials for applications as photocathodes in photoelectrochemical (PEC) H2 generation. A long-standing challenge for chalcopyrite semiconductors is characterizing their electronic structure—both experimentally and theoretically—due to their relatively high energy bandgaps and spin orbit coupling (SOC), respectively. In this work, we present single crystals of CuInTe2, whose relatively small optically measured bandgap of 0.9 ± 0.03 eV enables electronic structure characterization by angle-resolved photoelectron spectroscopy (ARPES) in conjunction with first-principle calculations incorporating SOC. ARPES measurements reveal bands that are steeply dispersed in energy with a band velocity of 2.5-5.4 x 105 m/s, almost 50% of the extremely conductive material graphene. Additionally, CuInTe2 single crystals are fabricated into electrodes to experimentally determine the valence band edge energy and confirm the thermodynamic suitability of CuInTe2 for water redox chemistry. The electronic structure characterization and band edge position presented in this work provide kinetic and thermodynamic factors that support CuInTe2 as a strong candidate for water reduction.
关键词： photoelectrochemical H2 generation,electronic structure,spin orbit coupling,chalcopyrite semiconductors,band velocity,valence band edge energy,Transition metal chalcogenides,angle-resolved photoelectron spectroscopy,water redox chemistry,CuInTe2
更新于2025-09-10 09:29:36
-
Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || In Situ Photoelectron Spectroscopy
摘要： X-ray photoelectron spectroscopy (XPS) is based on the photoelectric effect, which is the emission of electrons from a solid, liquid, or gas once excited with photons (ultraviolet radiation or X-rays or even g-rays) of sufficient energy. XPS measured thus the occupied states. It is not the intensity of the radiation, which causes the emission, but the wavelength l, which is related with their frequency n and energy Ephoton via the relations Ephoton = hn = hc/l of the photons. The kinetic energy Ekin of such photoelectrons yields a spectrum which allows for the determination of the binding energy EB of electrons expelled from the core levels, and the binding energy of hybridized states is Ekin = Ephoton - EB - 4spectrometer; 4 is the work function of the spectrometer. relationship between measured variables in the valence band. The quantitative
关键词： X-ray photoelectron spectroscopy,photoelectric effect,binding energy,work function,valence band
更新于2025-09-10 09:29:36