The influence of metal work function on the barrier heights of metal/pentacene junctions
The influence of metal work function on the barrier heights of metal/pentacene junctions
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DOI：
10.1063/1.2890415
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发表时间：
2008-03-15
影响因子：
3.2
通讯作者：
Parkinson, B. A.
中科院分区：
文献类型：
--
作者：
Jaeckel, B.;Sambur, J. B.;Parkinson, B. A.
利用光电子能谱分析了Cu(111)/并五烯和Ag(111)/并五烯界面的电子结构，确定了空穴势垒高度分别为0.74和0.90 eV。结合之前对Au(111)/并五苯界面的测量，确定肖特基势垒形成的金属功函数对势垒高度的斜率为0.36，与文献中的电流-电压（I-V）测量结果一致。然而，光发射测量的绝对势垒高度高出0.16 eV。I-V测量与x射线和紫外光电子能谱测量之间的偏移归因于如何确定最高占据分子轨道位置的差异。光电发射数据表明，在低覆盖度下，并五苯分子平躺在金属衬底上，而在高覆盖度下，分子取向发生变化，使长分子轴垂直于表面。然后，较厚的薄膜倾向于形成三维岛，从而在室温下在干净的Ag（111）和Cu（111）上形成结构化而不是扁平的薄膜。(C) 2008年美国物理研究所。
The electronic structure of Cu(111)/pentacene and Ag(111)/pentacene interfaces were investigated with photoelectron spectroscopy and the hole barrier heights were determined to be 0.74 and 0.90 eV, respectively. When combined with previous measurements of the Au(111)/pentacene interface, the slope of the plot of metal work function against barrier height for Schottky barrier formation was determined to be 0.36, in agreement with current-voltage (I-V) measurements in the literature. However, the absolute barrier heights from photoemission measurements are 0.16 eV higher. The offset between the I-V measurement and the x-ray and ultraviolet photoelectron spectroscopy measurements was attributed to differences in how the highest occupied molecular orbital position is determined. Photoemission data indicates that at low coverages the pentacene molecules lie flat on the metal substrates, whereas at higher coverages the molecular orientation changes to orient the long molecular axis normal to the surface. Thicker films then tend to form three-dimensional islands, resulting in structured rather than flat films forming on clean Ag(111) and Cu(111) at room temperature. (C) 2008 American Institute of Physics.