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Microscopy and Spectroscopy Study of Nanostructural Phase Transformation from β-MoO3 to Mo under UHV – MBE Conditions
摘要: We report a simple reduction of molybdenum oxide (β-MoO3) grown on reconstructed Si(100) by thermal annealing in ultra-high vacuum (UHV) using molecular beam epitaxy (MBE). By increasing the substrate temperature during deposition or the annealing temperature after growth, the morphologies of as-deposited structures were found to vary from nanoribbons (NRs) of β-MoO3 to nanoparticles (NPs) of Mo. The change in morphologies have been associated with a structural transition from β-MoO3 to MoO2 at 400 °C and MoO2 to Mo at 750 °C. The in-situ X-ray photoelectron spectroscopy (XPS) measurements revealed a shift of the Mo 3d peaks towards lower binding energies, representing the reduction in Mo oxidation states until a pure Mo 3d peak at 750°C was observed. The ex-situ KPFM measurements showed a decrease in the local work function (Φ) (from ≈ 5.27 ± 0.05 eV to ≈ 4.83 ± 0.05 eV) with increasing substrate temperature. A gradual reduction of the band gap from ≈ 3.32 eV for β-MoO3 NRs to zero band gap for Mo NPs is also observed during the annealing up to 750 °C.
关键词: in-situ XPS,KPFM,molecular beam epitaxy (MBE),Mo nanoparticles,β-MoO3 nanoribbons,phase transition
更新于2025-09-23 15:22:29
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In-situ XPS Study of Core-levels of ZnO Thin Films at the Interface with Graphene/Cu
摘要: We have investigated core-levels of ZnO thin films at the interface with the graphene on Cu foil using in-situ X-ray Photoelectron Spectroscopy (XPS). Spectral evolution of C 1s, Zn 2p, and O 1s are observed in real time during RF sputtering deposition. We found binding energy (BE) shifts of Zn 2p and ‘Zn?O’ state of O 1s depending on ZnO film thickness. Core-levels BE shifts of ZnO will be discussed on the basis of electron transfer at the interface and it may have an important role in the electronic transport property of the ZnO/graphene-based electronic device.
关键词: In-situ XPS,Electron transfer,Graphene,Thin film,ZnO,Dipole,Interface
更新于2025-09-09 09:28:46