visualization of Fermi level pinning sites at metal semiconductor interfaces

我们已经在我们的电子束真空扫描隧道显微镜上安装了弹道电子发射显微镜（BEEM）功能，现在正在检查其性能。我们建立了一个由电极，电馈通和一个转移杆组成的单元，这些都是BEEM所必需的，将其连接到电子束真空室，并检查它们是否正常工作。我们还开发了用于控制信号的电子设备，并调整了计算机辅助测量系统，以便进行BEEM成像和测量I-V谱。由于在本项目中制备具有低界面态密度的金属半导体界面非常重要，因此我们设置了一个手套箱，用于氧气，水和粒子浓度/密度非常小的样品的化学处理。我们开发了一种方法，使样品与理想的界面上的硅样品，但碳化硅，我们计划用于本研究，我们无法找到一个合适的条件的化学处理的无钉扎界面样品。我们还发展了一种提高原子力显微镜（AFM）空间分辨率的方法来观察钉扎位置。为了提高原子力显微镜的力灵敏度，我们努力减少电噪声和控制探针尖端的形状，成功地检测到一个单一的共价化学键，并采取了高分辨率的硅表面的图像。我们还尝试了表面电位剖面成像的测量，证实了这种电位剖面成像具有高灵敏度和高空间分辨率。我们还研究了用于制作金属半导体界面衬底的硅表面的基态结构。使用低温扫描隧道显微镜（STM）与准确的温度测量在样品位置，我们成功地确定了结构。

We have installed a function of ballistic electron emission microscopy (BEEM) on our ultrahigh vacuum scanning tunneling microscopy and are now checking its performance. We set up a unit composed of electrodes, electrical feedthough, and a transfer rod which are necessary for BEEM, attached it to the ultrahigh vacuum chamber, and checked they work properly. We also developed electronics for controlling the signal and adjusted computer-aided measurement system appropriately for taking the BEEM imaging and measuring I-V spectra.Since for this project it is very important to prepare metal semiconductor interfaces with a low density of interface states, we set up a glove box for the chemical processing of the samples in which concentration/density of oxygen, water and particle is extremely small. We developed a method to make samples with the ideal interface on silicon samples but for silicon carbide, which we planned to use for this study, we could not find an appropriate condition of the chemical processing for the pinning-less interface samples. We still need to work for that.We also developed a method of improving spatial resolution of atomic force microscopy (AFM) for the pinning site observation. With an intention of improving force sensitivity of AFM, we worked for reducing electrical noise and controlling the shape of the probe tip, successfully detected a single covalent chemical bonding, and took highly resolved images of silicon surfaces. We also tried for a measurement of surface potential profile imaging and confirmed that the potential imaging is taken with high sensitivity and high spatial resolutions.We also investigated the ground state structure of silicon surface, which is used to make metal semiconductor interfaces as a substrate. Using low temperature scanning tunneling microscopy (STM) with an accurate temperature measurement at the sample site, we successfully determined the structure.