Measurements of electronic properties of interfaces with functional nanostructures by bias-voltage non-contact atomic force microscopy/spectroscopy

本研究的目的是利用偏置电压非接触原子力显微镜/光谱学分析原子尺度上的光电功能纳米结构，以及它们的电子状态和与衬底的结合状态。结果表明，当我们使两个凝聚态相互靠近，并改变它们之间的偏置电压时，我们可以通过静电势能的变化来能量地调节两个表面的电子态，从而产生共振态，即共价键。此外，同时测量了它们之间的相互作用力，表明了评估隧道势垒坍塌的可能性，并分析了电子传导和力的关系。因此，我们推广了针尖制备技术，以提高电流和力的检测灵敏度。我们清洁了AFM悬臂梁上的硅针尖，并在上面沉积了Ge，或者用针尖接触加热的Ge或Si衬底，并加热和/或施加偏置电压：这导致了针尖上生长出纳米柱。用扫描电子显微镜、扫描电子显微镜和透射电子显微镜对其进行了表征。此外，我们制作了石英力传感器，并在电化学刻蚀的铂-IT线上制备了铂纳米管用于传感器。我们在原子尺度上观察了沉积在Si(111)-7x7上的4，4“-二氨基-对三联苯的π共轭分子，并用X射线光电子能谱分析了它们的电子结合态。DAT在线性分子的两端有两个氨基，有可能在硅衬底上形成长度可控的π偶联分子，这些分子通过与DAT交替沉积例如1，4-双(4-甲酰基苯乙烯基)苯进行气相聚合。我们观察到DAT优先吸附在7x7重建的缺陷半细胞上，并在DAT结束时得到一个氨基与硅底物结合，另一个氨基游离的证据。此外，我们还得出结论：与硅结合的氨基对衬底具有导电性。

The aim of this study is to analyze opto-electronic functional nanostructures on atomic scale, and their electronic and binding states to substrates using bias-voltage non-contact atomic force microscopy/spectroscopy. The results showed that, when we brought two pieces of condensed matter close to each other, and changed bias voltage across them, we can energetically tune the electronic states at the two surfaces through the change in electrostatic potential energy, resulting in resonating states, i.e. covalent bond. In addition, simultaneous measurements of interaction force with current between them implied that the possibility of evaluating collapse of tunneling barrier and analyzing the correlation between electronic conduction and force. Thus, we promoted the tip preparation techniques to improve the detection sensitivity of current and force. We cleaned Si tips on AFM cantilevers, and deposited Ge on them or touch heated Ge or Si substrates with the tip, and heated and/or applied bias voltage: this leads to growth of a nanopillar on the tip. We evaluated them with SEM, SAM and TEM. Moreover, we fabricated quartz force sensors and prepared Pt nanopillars on electrochemically etched Pt-It wire for the sensors. We observed π-conjugated molecules of 4,4"-diamino-p-terphenyl (DAT) deposited on Si(111)-7x7 on atomic scale and analyzed their electronic binding states by XPS. DAT has two amino groups at both ends of the linear molecule with potential to form π-conjugated molecules with a controlled length standing on Si substrates, which are vapor polymerized by depositing, e.g., 1,4-bis (4-formylstyryl) benzene alternatively with DAT. We observed that DAT was adsorbed preferentially on faulted half cells of the 7x7 reconstruction, and obtained evidence that one amino group is bound with Si substrate and the other is free at the end of DAT. Moreover, we concluded that the amino group binding with Si exhibited electric conduction to the substrate.