Liu Yucong, He Jiayu, Kwon Osung, Zhu Da-Ming
Department of Physics, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA.
Rev Sci Instrum. 2012 Jan;83(1):013701. doi: 10.1063/1.3673476.
We have analyzed correlations between surface morphology and current sensing images obtained using a current sensing atomic force microscope (CSAFM) and the implication of surface conductivity derived from the current sensing images. We found that in cases where the diameter of a CSAFM probe tip is much smaller than the correlation length of the surface morphological features, the current detected using the probe should have little correlation with the surface features imaged by the same probe. If the sample thickness is much larger than the tip size, the surface conductivity distribution of a sample can be derived from a current sensing image using the Holm resistance relation, and the current probed using a CSAFM reflects the conductance variations in a layer on the surface with the thickness comparable to the probe diameter. However, if the thickness of a sample is comparable to or smaller than the tip diameter, CSAFM measures the conductance across the entire portion of the sample sandwiched between the tip and the electrode.
我们分析了使用电流传感原子力显微镜（CSAFM）获得的表面形态与电流传感图像之间的相关性，以及从电流传感图像得出的表面电导率的含义。我们发现，在CSAFM探针尖端的直径远小于表面形态特征的相关长度的情况下，使用该探针检测到的电流与同一探针成像的表面特征几乎没有相关性。如果样品厚度远大于尖端尺寸，则可以使用霍尔姆电阻关系从电流传感图像中得出样品的表面电导率分布，并且使用CSAFM探测的电流反映了表面上厚度与探针直径相当的一层中的电导变化。但是，如果样品的厚度与尖端直径相当或小于尖端直径，则CSAFM测量的是夹在尖端和电极之间的整个样品部分的电导。
