Characterization of tips for conducting atomic force microscopy in ultrahigh vacuum
Characterization of tips for conducting atomic force microscopy in ultrahigh vacuum
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DOI：
10.1063/1.1148838
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发表时间：
1998-04-01
影响因子：
1.6
通讯作者：
Welland, ME
中科院分区：
文献类型：
--
作者：
Lantz, MA;O'Shea, SJ;Welland, ME
我们已经调查了各种金属涂层和半导体尖端的可靠性进行原子力显微镜实验中使用的超高真空（UHV）的环境。为了获得可靠的传导数据，我们发现有必要首先使用短氩离子溅射清洁尖端。扫描透射电子显微镜是用来成像后的导电性实验，并发现是非常有用的评估尖端磨损和解释导电性数据。尖端的可靠性被发现是强烈依赖于样品和实验条件。磨损和污染的尖端被发现是严重的问题，这是有关的尖端样品粘附。我们说明了这些影响，并突出了一些常见的可靠性问题，我们遇到了使用具体的例子。一般来说，我们发现金属涂层尖端不足以获得可重复的数据，特别是如果侧向力施加在尖端上。均匀的半导体尖端，一旦清洗，被发现是令人满意的，并在空气中进行的实验的一个特定的对比是，硅尖可以可靠地使用。此外，我们发现，在特高压，导电实验可以可靠地进行，即使在非常低的作用力，纳米牛顿的顺序。与在空气中进行的实验相比，这是一个明显的优势，当存在表面污染时，通常需要微牛顿量级的作用力来建立稳定的电接触。(C)1998年美国物理学会。【S0034-6748（98）00504-X】。
We have investigated the reliability of a variety of metal coated and semiconductor tips for use in conducting atomic force microscopy experiments in an ultrahigh vacuum (UHV) environment. In order to obtain reliable conduction data we find it necessary to first clean the tips using a short argon ion sputter. Scanning transmission electron microscopy is used to image tips after the conductivity experiments and found to be very useful for assessing tip wear and interpreting conductivity data. Tip reliability is found to be strongly dependent on the sample and the experimental conditions. Wear and contamination of the tip are found to be severe problems which are related to the tip-sample adhesion. We illustrate these effects and highlight some of the common reliability problems which we encountered using specific examples. In general, we find that metal coated tips are not reliable enough to obtain repeatable data, especially if lateral forces are exerted on the tip. Homogeneous semiconductor tips, once cleaned, are found to be satisfactory and a particular contrast with experiments performed in air is that Si tips can be used reliably. In addition we find that in UHV, conduction experiments may be reliably performed even at very low applied force, of order nano-Newtons. This is a clear advantage in comparison to experiments performed in air when surface contamination is present and applied forces on the order of micro-Newtons are often required to establish stable electrical contact. (C) 1998 American Institute of Physics. [S0034-6748(98)00504-X].