Mn/PbTe(111)界面行为的光电子能谱研究

Mn/PbTe(111) interface behavior studied by photoemission

利用X光电子能谱(XPS)对Mn在PbTe(111)表面上沉积生长的界面性质进行了研究.研究表明Mn的沉积使衬底发生了原子尺度上的突变及金属/半导体界面的形成.从X光电子能谱的芯态能级峰来看,随着Mn膜的沉积Pb4f峰的低结合能端出现了金属Pb的特征新峰,而Te3d峰的高结合能端却出现了MnTe特征新峰.且随着Mn膜厚度的增加这些新峰变得越来越明显,当Mn膜厚度超过7ML(monolayer)(即超过Pb,Te的探测深度)时,衬底信号峰完全消失,只剩下金属Pb和MnTe的芯态能级峰.Mn膜厚度继续增加时,金属Pb芯态能级峰的峰强在误差范围内基本保持不变,而具有MnTe特性的Te的芯态能级峰峰强呈明显下降趋势,当膜厚为102ML时,几乎已经探测不到Te的芯态峰,而金属Pb的芯态峰却仍然较强.由此可以推测随着金属Mn膜的沉积,衬底原子Pb和Te均向金属层发生了不同程度的偏析.偏析的Te以MnTe化合物的形式被束缚在Mn金属生长层中,而偏析的Pb则以金属Pb的形式漂浮在Mn生长层的最表面.

We performed X-ray photoemission spectroscopy （XPS） investigation on the interface behavior at the Mn/PbTe（111） interface. The measurement shows the drastic changes at atomic level and the Mn/PbTe（111） interface formation. Upon Mn deposition, a new peak component associated with metallic Pb appears in the Pb core-level at low binding energies, and a new peak component related to MnTe compound appears in the Te core-level at high binding energies. These new features become more and more obvious in XPS spectra with increasing Mn thickness, and at the Mn thickness higher than 7 ML （beyond the escape depths of Pb and Te）, the substrate features disappear. Upon further deposition of Mn, the intensity of the metallic Pb core level keeps constant, while the intensity of Te 3d core level of MnTe compound decreases with increasing Mn thickness, and finally the Te 3d core level disappears at Mn thickness of about 102 ML. Based on these results, we can conclude that, upon Mn depostion, both Te and Pb segregate to the surface region, the segregated Pb as metallic Pb floats on the top of Mn overlayer, and the segregated Te is bound in the Mn overlayer as MnTe.