Piquemal François, Morán-Meza José, Delvallée Alexandra, Richert Damien, Kaja Khaled
Laboratoire National de Métrologie et d'Essais (LNE), 78197 Trappes, France.
Nanomaterials (Basel). 2021 Mar 23;11(3):820. doi: 10.3390/nano11030820.
Reference samples are commonly used for the calibration and quantification of nanoscale electrical measurements of capacitances and dielectric constants in scanning microwave microscopy (SMM) and similar techniques. However, the traceability of these calibration samples is not established. In this work, we present a detailed investigation of most possible error sources that affect the uncertainty of capacitance measurements on the reference calibration samples. We establish a comprehensive uncertainty budget leading to a combined uncertainty of 3% in relative value (uncertainty given at one standard deviation) for capacitances ranging from 0.2 fF to 10 fF. This uncertainty level can be achieved even with the use of unshielded probes. We show that the weights of uncertainty sources vary with the values and dimensions of measured capacitances. Our work offers improvements on the classical calibration methods known in SMM and suggests possible new designs of reference standards for capacitance and dielectric traceable measurements. Experimental measurements are supported by numerical calculations of capacitances to reveal further paths for even higher improvements.
参考样品通常用于扫描微波显微镜（SMM）及类似技术中电容和介电常数纳米级电学测量的校准和定量。然而，这些校准样品的可追溯性尚未建立。在这项工作中，我们详细研究了影响参考校准样品电容测量不确定度的最可能误差源。我们建立了一个全面的不确定度预算，对于0.2 fF至10 fF范围内的电容，相对值的合成不确定度为3%（不确定度以一个标准偏差给出）。即使使用非屏蔽探头也能达到这个不确定度水平。我们表明，不确定度源的权重随测量电容的值和尺寸而变化。我们的工作改进了SMM中已知的经典校准方法，并提出了用于电容和介电可追溯测量的参考标准的可能新设计。实验测量得到了电容数值计算的支持，以揭示进一步实现更高改进的途径。
