Surface "element" imaging by a new scanning probe microscopy

本项目的主要研究成果如下：2001(1)将本项目研制的新型探针显微镜安装在同步辐射装置SPRING-8的光束线上。我们发现在x射线辐照下，由内层激发引起的价态调制可以通过电容来检测。(2)微探针探测到的局域电容的光子能量依赖关系表明样品表面存在x射线吸收精细结构(XAFS)谱。这一发现表明，该方法可以获得具有表面化学信息的扫描图像，如元素及其成键状态。(3)我们展示了一种先进的位选择性；(4)作为这种方法的工业应用，我们成功地观察到了晶体管中厚度为~nm的导电沟道的位选择性XAFS谱。2002(1)我们观察了各种样品表面，并且达到了我们的项目目标：建立了表面元素成像技术。(2)该技术的优势在我们的研究中得到了典型的体现：半导体表面超薄氧化物中电子陷阱的元素和结构分析。(3)成功地实现了微探针对局域结构及其电学性质的同时测量。(4)这种电容检测技术揭示了掩埋量子点结构的界面状态。这种技术所涉及的位置选择性使我们有可能分析纳米电子器件的内部。(5)XAFS光谱可以通过分子轨道计算来预测。这一结果表明了该方法的可靠性，并为频谱分析提供了一般的指导方针。

The main research results related to this project are as follows.2001(1)We installed a new probe microscopy developed in this project into a beamline of the synchrotron radiation facility, Spring-8. We found that a valence state modulation owing to an inner-shell excitation can be detected by capacitance under the x-ray irradiation.(2)The photon energy dependence of a local capacitance detected by the microprobe indicated an x-ray absorption fine structure (XAFS) spectrum of the sample surface. This finding indicates that the scanning image with surface chemical information, such as element and its bonding states, can be obtained by this method.(3)We demonstrated an advanced site-selectivity ; the control of bias voltage applied to the microprobe selects the observable bonding state.(4)As an industrial application of this method, we successfully observed the site-selective XAFS spectrum of a conduction channel with 〜nm thickness in a transistor.2002(1)We observed various sample surfaces, and reached our project goal: establishment of the surface "element" imaging technique.(2)The advantage of this technique is typically shown in our research: element and structure analyses of electron trap in ultra-thin oxide on semiconductor surface.(3)Simultaneous measurement of the local structure and its electric property by the microprobe is successfully achieved.(4)This capacitance detection technique revealed the interface state of buried quantum dot structure. The site-selectivity involved in this technique makes us possible to analyze the inside of the nano-electric devices.(5)The XAFS spectrum is predictable by molecular orbital calculation. This result shows the reliability and a general guideline for spectrum analysis of this method.