Structural change of radiation defects in graphite crystals induced by STM probing
Structural change of radiation defects in graphite crystals induced by STM probing
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STM探测引起石墨晶体辐射缺陷的结构变化
DOI：
10.1007/s003390101025
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
K. Maeda
中科院分区：
文献类型：
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作者：
O. Tonomura;Y. Mera;A. Hida;Y. Nakamura;T. Meguro;K. Maeda
研究发现，在超高真空条件下，400 eV Ar+离子轰击高取向热解石墨引入缺陷的扫描隧道显微镜(STM)图像在STM探测过程中发生了实质性的变化。对电压扫描期间在缺陷处测量到的隧道电流突变的详细检查表明，缺陷图像变化的主要原因既不是注入电流也不是注入功率，而是施加在探头尖端和样品之间的电压的绝对值。我们认为，极化诱导力将样品表面吸引到探针尖端，使石墨表面的层间距变宽，导致离子辐照引起的间隙原子的横向扩散加速，从而导致扫描电子显微镜成像中敏感的缺陷结构和伴随的电子结构的变化。
It was found that STM (scanning tunneling microscopy) images of defects in highly oriented pyrolytic graphite introduced by bombardment of 400 eV Ar+ions in ultra-high vacuum exhibit substantial changes in the course of STM probing. Detailed examination of abrupt changes in the tunneling current measured at defect sites during voltage scans shows that the primary cause of the defect-image change was found to be neither the injected current nor the injected power but the absolute value of the voltage applied between the probe tip and the sample. We propose that an electric polarization induced force attracting the sample surface toward the probe tip widens the layer spacing of the graphite surface, leading to an acceleration of the lateral diffusion of interstitial atoms introduced by the ion irradiation, which results in a change in the defect structures and the accompanying electronic structures sensible in the STMimaging.