Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Rige, Tennessee 37831, United States.
ACS Nano. 2014 Oct 28;8(10):10229-36. doi: 10.1021/nn505176a. Epub 2014 Oct 2.
The implementation of contact mode Kelvin probe force microscopy (cKPFM) utilizes the electrostatic interactions between tip and sample when the tip and sample are in contact with each other. Surprisingly, the electrostatic forces in contact are large enough to be measured even with tips as stiff as 4.5 N/m. As for traditional noncontact KPFM, the signal depends strongly on electrical properties of the sample, such as the dielectric constant, and the tip properties, such as the stiffness. Since the tip is in contact with the sample, bias-induced changes in the junction potential between tip and sample can be measured with higher lateral and temporal resolution compared to traditional noncontact KPFM. Significant and reproducible variations of tip-surface capacitance are observed and attributed to surface electrochemical phenomena. Observations of significant surface charge states at zero bias and strong hysteretic electromechanical responses at a nonferroelectric surface have significant implications for fields such as triboelectricity and piezoresponse force microscopy.
接触模式原子力显微镜（cKPFM）的实现利用了针尖和样品在接触时相互之间的静电相互作用。令人惊讶的是，即使使用像 4.5 N/m 这样硬的针尖，接触产生的静电力也大到足以进行测量。对于传统的非接触 KPFM，信号强烈依赖于样品的电特性，如介电常数，以及针尖的特性，如硬度。由于针尖与样品接触，因此可以以比传统的非接触 KPFM 更高的横向和时间分辨率来测量由于偏压引起的针尖与样品之间的结电位变化。观察到显著的和可重复的针尖-表面电容变化，并归因于表面电化学现象。在零偏压下观察到显著的表面电荷状态和在非铁电表面上的强滞后机电响应，这对摩擦电和压电力显微镜等领域具有重要意义。
