Fe/ZnO(000■)界面的同步辐射光电子能谱研究

Synchrotron radiation photoemission studies on Fe/ZnO(0001) interface

利用同步辐射光电子能谱研究了Fe/ZnO生长模式、界面化学反应和电子结构.结果表明,Fe在ZnO(000■)表面以类SK模式生长(单层加岛状生长).当沉积约2的Fe后,生长模式开始从二维层状生长转变成混合模式生长.界面价带谱和Fe3p芯能级谱的分析表明,在低覆盖度下,约有一个原子层(约1.5)的Fe被ZnO(000■)面的外层O原子氧化,随着沉积厚度的增加,金属态Fe的信号逐渐增强.当吸附了5.1的Fe时,出现了较强的金属Fe的Fermi边,说明出现了Fe的金属态.此外,在Fe原子吸附过程中,样品功函数在Fe厚度为0.2时达到最小值4.5eV,偶极层形成后逐渐稳定在4.9eV.

The growth, interfacial reaction, and electronic structure of Fe on ZnO（0001^- ） surface were studied using synchrotron radiation photoemission spectroscopy（SRPES）. It was found that Fe layer grows in a way similar to the Stranski-Krastanov mode at room temperature. After - 2 A Fe deposited on the surface, the growth mode changes from the layer-by-layer to a mixed mode. At low coverage, about one monolayer of iron （ca. 1,5 A） is oxidized by the outer oxygen atoms on ZnO（0001^-） surface. Analysis of the valence band and the Fe3p photoemission spectra indicated that below 2 A coverage, Fe^2＋ species exists at the Fe/ZnO interface, followed by the formation of a metallic iron overlayer. A sharp Fermi edge appears at 5.1 A coverage, indicating the formation of the bulk metallic Fe film. Furthermore, work-function of the sample decreases to a minimum of 4.5 eV at 0. 2 A Fe, then goes to 4.9 eV with the formation of a dipole layer at the interface.