研究目的
To study the growth and surface structure of tin oxide films on Ag(001) substrate at both room temperature and high temperature, and to differentiate between the stannic and stannous oxides formed during the process.
研究成果
The study confirmed the coexistence of both SnO and SnO2 at RT with more SnO being formed at higher coverage. At HT, only one oxidised phase of tin oxide mainly due to SnO2 was formed for most of the coverage. The presence of SnO was also confirmed only at the highest coverage studied here for HT. The structural phase change was observed by LEED where a square 4-fold multidomain pattern was noticed for low coverage which changed to the hexagonal multidomain pattern for higher coverages at HT growth.
研究不足
The study is limited by the difficulty in differentiating between stannic and stannous oxides due to very small shift in the binding energies of the XPS core levels. Also, non-availability of large single crystals of tin oxide makes it difficult to study surface properties and electronic structure.
1：Experimental Design and Method Selection:
Tin oxide films were grown on Ag(001) substrate by reactive deposition of Sn in an O2 atmosphere at both room temperature (RT) and high temperature (HT) at 573 K. The films were studied using x-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED), and ultraviolet photoemission spectroscopy (UPS).
2：Sample Selection and Data Sources:
A well-ordered Ag(001) single crystal substrate was prepared by repeated cycles of Ar+ ion sputtering followed by annealing. High purity Sn was evaporated in the preparation chamber from a homemade resistive-type evaporator.
3：List of Experimental Equipment and Materials:
A four-grid LEED apparatus coupled with a highly-sensitive 12-bit CCD camera, VG SCIENTA-R4000WAL electron energy analyzer with a 2D-CCD detector, and an Al Kα monochromatic X-ray source (1486.6 eV) from VG Scienta were used for measurements.
4：6 eV) from VG Scienta were used for measurements.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Sn was deposited on the substrate in the oxygen atmosphere by leaking oxygen into the vacuum chamber. LEED and XPS measurements were performed at RT.
5：Data Analysis Methods:
The binding energy of each peak was calculated by fitting the curve with CasaXPS software. The valence band of grown tin oxide films was studied using He IIα photon with energy 40.8 eV.
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