Tip-Sample Interactions in Kelvin Probe Force Microscopy: Quantitative Measurement of the Local Surface Potential
Tip-Sample Interactions in Kelvin Probe Force Microscopy: Quantitative Measurement of the Local Surface Potential
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DOI：
10.1021/jp806657k
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发表时间：
2008-11-06
影响因子：
3.7
通讯作者：
Samori, Paolo
中科院分区：
文献类型：
--
作者：
Liscio, Andrea;Palermo, Vincenzo;Samori, Paolo
研究了开尔文探针力显微镜(KPFM)测量中不同实验参数对探针与样品相互作用的影响。我们提供了清洁的宏观高度定向热解石墨(HOPG)样品的局部表面电势(SP)的精确和可重复性的测定，以及在表面自组装的烷基取代二茂铁(PDI)的有机半导体纳米结构的测定。我们在测量的SP中区分了两个不同的术语，本征和外在，分别包含研究对象和实验伪迹的电学性质。我们研究了最相关的实验参数，包括针尖-样品距离、相对湿度(RH)和施加在针尖上的电势，这些参数决定了所测量的SP的外部项。此外，我们设计了针尖-样品相互作用的理论描述，考虑了在KPFM扫描过程中由于施加交流电势而引起的探头的额外调制。通过对空气环境中影响SP测量的所有术语的深入理解，可以设计一种新的协议来量化纳米物体的电学性质，从而提高获得的横向分辨率，所提出的模型与实验结果之间的良好一致性证明了这一点。
We study the influence of different experimental parameters on the interaction between the probe and the sample in Kelvin probe force microscopy (KPFM) measurements. We provide a precise and reproducible determination of the local surface potential (SP) of clean macroscopic highly oriented pyrolytic graphite (HOPG) samples and of organic semiconducting nanostructures of an alkyl-substituted perylene-bis(dicarboximide) (PDI) self-assembled at surfaces. We distinguish two different terms in the measured SP, intrinsic and extrinsic, containing the electrical properties of the studied object and the experimental artifacts, respectively. We investigate the effect of the most relevant experimental parameters including tip-sample distance, relative humidity (RH), and potential applied to the tip, which govern the extrinsic term of the measured SP. Moreover, we devise a theoretical description of the tip-sample interaction taking into account the extra modulation of the probe due to the applied ac potential during the KPFM scan. A deep understanding of all the terms which contribute to the measured SP in air environment made it possible to devise a new protocol to quantify the electrical properties of nano-objects leading to an improvement of the achieved lateral resolution, as demonstrated by the good agreement between the proposed model and the experimental results.