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Observation of Electron-Wave Diffraction with Scanning Probe based on Reciprocity Principle

基于互易原理的扫描探针电子波衍射观测

基本信息

批准号：
15360184
负责人：
FURUYA Kazuhito
金额：
$ 8.83万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15360184/
关键词：
scanning probe hot electron electron diffraction BEEM reciprocity principle quantum effect device Fourier Transformation by electron wave FDTD method for quantum mechanics 電子波回折相反原理電子波フーリエ変換デバイス弾道電子放出顕微鏡量子相反性波面位相シフタバリシ

项目摘要

In order to observe diffraction phenomena of hot electrons in solids using scanning probes based on the reciprocity principle, theoretical simulations have been performed to find required current sensitivity pico-ampere(pA) level. Experimentally, the Ballistic Electron Emission Microscopy(BEEM) technique has been improved to obtain uniform current signal in pA level over sample surfaces.Three-dimensional Schroedinger equation was numerically analyzed using the finite-difference time-domain(FDTD) method with absorbing boundaries. Appling this analysis to phase-shifter structures, followings have been clarified ; conditions of the energy width of the injected electron to obtain the diffraction fringe with pA variation, conditions for spherical wave generation in semiconductors. It has been found that the diffraction caused by constriction of the electron beam reduces the transmission efficiency by factor 5. We have proposed to take this diffraction effect into account in BEEM analyses.A … More BEEM apparatus has been constructed based on existing scanning tunnel microscope by installing the control system bought newly. Using GaAs/Au Schottky samples, current sensitivity of pA has been achieved by eliminating noises. Strategy for the probe scanning has been developed to obtain two-dimensional image of BEEM signal ; the probe stays at one point for a period required to eliminate the noise.In order to obtain uniform BEEM signal over the surface, intact and clean Schottky interfaces have been created by devising a novel self-alignment process. Finally it has been revealed that grain formations in 10 nm-thick Au films limit uniformity in BEEM signal in the sample surface.In summary, we have clarified possibilities and conditions to observe the electron wave diffraction in the solid by probes based on the reciprocity principle and established the BEEM technique as foundations to achieve the observation. We have approached to the target leaving a final step to form the conductive surface layer by epitaxy. Less

为了利用基于互易原理的扫描探针观察固体中热电子的衍射现象，进行了理论模拟，找出了所需的电流灵敏度皮安（pA）水平。实验上，改进了弹道电子发射显微镜（BEEM）技术，使其在样品表面上获得均匀的pA级电流信号。采用带吸收边界的时域有限差分法对三维薛定谔方程进行了数值分析。将这一分析应用于移相器结构，阐明了以下几点：获得随pA变化的衍射条纹的注入电子能量宽度的条件，半导体中产生球形波的条件。发现电子束收缩引起的衍射使透射效率降低了5倍。我们建议在BEEM分析中考虑这种衍射效应。在现有扫描隧道显微镜的基础上，通过安装新购买的控制系统，构建了更多的BEEM仪器。利用GaAs/Au肖特基样品，通过消除噪声实现了pA的电流灵敏度。提出了一种探针扫描策略，以获取BEEM信号的二维图像；探头在一个点停留一段时间以消除噪声。为了在表面上获得均匀的BEEM信号，通过设计一种新颖的自对准过程，创建了完整而干净的肖特基界面。最后揭示了10 nm厚Au薄膜中的晶粒结构限制了样品表面BEEM信号的均匀性。综上所述，我们明确了基于互易原理的探针观察固体中电子波衍射的可能性和条件，并建立了BEEM技术作为实现观测的基础。我们已经接近目标，剩下最后一步是通过外延形成导电表面层。少