Synchrotron X-ray Photoelectron Spectroscopy Study of Electronic Changes at the ZnO Surface Following Aryldiazonium Ion Grafting: A Metal-to-Insulator Transition
Synchrotron X-ray Photoelectron Spectroscopy Study of Electronic Changes at the ZnO Surface Following Aryldiazonium Ion Grafting: A Metal-to-Insulator Transition
复制标题
芳基重氮离子接枝后 ZnO 表面电子变化的同步辐射 X 射线光电子能谱研究：金属到绝缘体的转变
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
M. Allen
中科院分区：
文献类型：
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作者：
A. R. McNeill;Kalib J. Bell;A. R. Hyndman;R. M. Gazoni;R. Reeves;A. Downard;M. Allen
ZnO是包括In2O3， SnO2， CdO和InN在内的一小类半导体的一员，它们的表面非常不寻常，因为它们的电子能带向下弯曲形成量子化势阱，其中二维电子气体被限制在其中。在o极性ZnO（0001）表面，这种效应是由吸附H原子产生羟基端接表面引起的。在这项工作中，我们研究了共价锚定的有机层对ZnO（0001）表面能带弯曲的影响。我们使用芳基重氮盐电化学沉积4- 5 nm厚的4-硝基苯基（NP）和4-（三氟甲基）苯基（TFMP）基团层。同步加速器x射线光电子能谱（XPS）表明，NP和TFMP修饰都永久地消除了ZnO表面向下的能带弯曲。这种行为可以用芳基与表面的直接共价键来解释，XPS分析也揭示了这一点，以及两种改性剂的吸电子特性。令人惊讶的是，我…
ZnO is a member of a small class of semiconductors that includes In2O3, SnO2, CdO, and InN, whose surfaces are highly unusual because their electronic bands bend downward to form a quantized potential well in which a two-dimensional electron gas is confined. At the O-polar ZnO(0001) surface, this effect arises from the adsorption of H adatoms which produces a hydroxyl-terminated surface. In this work, we investigate the effect of covalently anchored organic layers on the band bending at ZnO(0001) surfaces. We use aryldiazonium salt electrochemistry to deposit 4–5 nm thick layers of 4-nitrophenyl (NP) and 4-(trifluoromethyl)phenyl (TFMP) groups. Synchrotron X-ray photoelectron spectroscopy (XPS) showed that both NP and TFMP modifications permanently removed the downward band bending at the ZnO surface. This behavior can be explained by the direct covalent bonding of the aryl groups to the surface, also revealed by XPS analysis, and the electron-withdrawing character of both modifiers. Surprisingly, the i...