Sakuda Yusuke, Asahina Shunsuke, Togashi Takanari, Terasaki Osamu, Kurihara Masato
JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo196-8558, Japan.
Yamagata University, 1-4-12, Kojirakawamachi, Yamagata990-0021, Japan.
Microsc Microanal. 2020 Aug;26(4):758-767. doi: 10.1017/S1431927619015150.
Surface-sensitive information on a bulk sample can be obtained by using a low incident electron energy (low accelerating voltage/landing voltage) in a scanning electron microscope (SEM). However, topography and composition contrast obtained at low incident electron energies may not be intuitive and should be analyzed carefully. By combining an Auger electron spectrometer (AES) with a low incident electron energy SEM (LE-SEM), we investigated the SEM contrast carefully by separating the secondary electron (SE) and back-scattered electron (BSE) components with high accuracy. For this, we modified an AES to measure the electron energy in the range of 0–0.6 keV with a sample bias voltage of 0 to −0.3 keV. We could clearly observe reversed brightness of gold and carbon (graphite) in BSE images when the energy of the incident electrons was reduced to 0.2–0.3 keV. In addition, reflected electron energy spectroscopy (REELS) is known to be a tool for chemical state analysis of the sample. We demonstrated that it is possible to study the electron states of graphite, diamond, and graphene by acquiring low incident energy REELS spectra from their surfaces with the newly modified AES. This will be a new method for analyzing the electron states of local areas of a surface.
通过在扫描电子显微镜（SEM）中使用低入射电子能量（低加速电压/着陆电压），可以获取块状样品的表面敏感信息。然而，在低入射电子能量下获得的形貌和成分对比度可能不直观，需要仔细分析。通过将俄歇电子能谱仪（AES）与低入射电子能量SEM（LE-SEM）相结合，我们通过高精度分离二次电子（SE）和背散射电子（BSE）成分，仔细研究了SEM对比度。为此，我们对AES进行了改进，以在0至-0.3 keV的样品偏置电压下测量0-0.6 keV范围内的电子能量。当入射电子能量降低到0.2-0.3 keV时，我们可以在BSE图像中清楚地观察到金和碳（石墨）的亮度反转。此外，反射电子能量损失谱（REELS）是一种用于样品化学状态分析的工具。我们证明，通过使用新改进的AES从石墨、金刚石和石墨烯表面获取低入射能量REELS光谱，可以研究它们的电子态。这将是一种分析表面局部区域电子态的新方法。
