STEM Imaging with Beam-Induced Hole and Secondary Electron Currents
STEM Imaging with Beam-Induced Hole and Secondary Electron Currents
复制标题
DOI：
10.1103/physrevapplied.10.044066
复制
发表时间：
2018-10-29
影响因子：
4.6
通讯作者：
Regan, B. C.
中科院分区：
文献类型：
--
作者：
Hubbard, William A.;Mecklenburg, Matthew;Regan, B. C.
在标准电子束感应电流（EBIC）成像中，扫描电子束产生由样品内电场分离的电子空穴对，从而在样品中产生电流。在标准扫描电子显微镜（SEM）中，扫描电子束发射二次电子（SE），其远离样品被检测到。虽然扫描透射电子显微镜（STEM）中的电子束可以产生许多电子-空穴对，但对于60-300 keV范围内的电子束能量，SE的产率仅为百分之几，使得后一种信号更难以在样品上检测为EBIC。在这里，我们表明，在STEM中的样本EBIC注册SE发射和SE捕获作为空穴和电子，分别。检测两个电荷载流子产生标准的离样本SE成像无法达到的差分图像对比度。在包含两个电流放大器的双EBIC成像配置中，甚至可以同时捕获两个电荷载流子。与标准EBIC成像中产生的电流相比，标准EBIC成像仅突出显示样品中包含电场的区域，SE发射产生的EBIC或SEEBIC很小（皮安级）。但是SEEBIC成像可以在样品的任何地方产生对比度，暴露出纳米电子器件中的掩埋界面，连接性和其他感兴趣的电子特性，甚至在金属和其他没有内部电场的结构中。
In standard electron-beam-induced-current (EBIC) imaging, the scanning electron beam creates electron-hole pairs that are separated by an in-sample electric field, producing a current in the sample. In standard scanning electron microscopy (SEM), the scanning electron beam ejects secondary electrons (SEs), which are detected away from the sample. While a beam electron in a scanning transmission electron microscope (STEM) can produce many electron-hole pairs, the yield of SEs is only a few percent for beam energies in the range 60-300 keV, making the latter signal much more difficult to detect on sample as an EBIC. Here we show that the on-sample EBIC in a STEM registers both SE emission and SE capture as holes and electrons, respectively. Detecting both charge carriers produces differential image contrast not accessible with standard, off-sample SE imaging. In a double EBIC-imaging configuration incorporating two current amplifiers, both charge carriers can even be captured simultaneously. Compared with the current produced in standard EBIC imaging, which highlights only the regions in a sample that contain electric fields, the EBIC produced by SE emission, or SEEBIC, is small (picoampere scale). But SEEBIC imaging can produce contrast anywhere in a sample, exposing the texture of buried interfaces, connectivity, and other electronic properties of interest in nanoelectronic devices, even in metals and other structures without internal electric fields.