Kelvin Probe Force Microscopy and Calculation of Charge Transport in a Graphene/Silicon Dioxide System at Different Relative Humidity,ACS Applied Materials & Interfaces

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Kelvin Probe Force Microscopy and Calculation of Charge Transport in a Graphene/Silicon Dioxide System at Different Relative Humidity
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2018-03-20 00:00:00 , DOI: 10.1021/acsami.7b18041
Martin Konečný _{1,

2} , Miroslav Bartošík _{1,

2,

3} , Jindřich Mach _{1,

2} , Vojtěch Švarc _{1,

2} , David Nezval _{1,

2} , Jakub Piastek _{1,

2} , Pavel Procházka _{1,

2} , Aleš Cahlík ₄ , Tomáš Šikola _{1,

2}

Affiliation

The article shows how the dynamic mapping of surface potential (SP) measured by Kelvin probe force microscopy (KPFM) in combination with calculation by a diffusion-like equation and the theory based on the Brunauer–Emmett–Teller (BET) model of water condensation and electron hopping can provide the information concerning the resistivity of low conductive surfaces and their water coverage. This is enabled by a study of charge transport between isolated and grounded graphene sheets on a silicon dioxide surface at different relative humidity (RH) with regard to the use of graphene in ambient electronic circuits and especially in sensors. In the experimental part, the chemical vapor-deposited graphene is precisely patterned by the mechanical atomic force microscopy (AFM) lithography and the charge transport is studied through a surface potential evolution measured by KPFM. In the computational part, a quantitative model based on solving the diffusion-like equation for the charge transport is used to fit the experimental data and thus to find the SiO₂ surface resistivity ranging from 10⁷ to 10¹⁰ Ω and exponentially decreasing with the RH increase. Such a behavior is explained using the formation of water layers predicted by the BET adsorption theory and electron-hopping theory that for the SiO₂ surface patterned by AFM predicts a high water coverage even at low RHs.

中文翻译：

不同相对湿度下的石墨烯/二氧化硅体系中的开尔文探针力显微镜和电荷传输的计算

本文介绍了如何通过开尔文探针力显微镜（KPFM）结合通过类似扩散的方程式和基于Brunauer-Emmett-Teller（BET）模型的水凝结理论进行计算来测量表面势（SP）的动态映射电子跳跃可以提供有关低导电表面的电阻率及其水覆盖率的信息。关于在环境电子电路中，尤其是在传感器中使用石墨烯的研究，通过研究在不同相对湿度（RH）的二氧化硅表面上隔离的和接地的石墨烯片之间的电荷传输，可以实现这一点。在实验部分，通过机械原子力显微镜（AFM）光刻对化学气相沉积的石墨烯进行精确图案化，并通过KPFM测量的表面电势演化研究电荷传输。在计算部分，使用基于求解电荷迁移的扩散式方程的定量模型来拟合实验数据，从而找到SiO₂表面电阻率范围为10 ⁷到¹⁰ 10Ω，并且随着RH的增加呈指数下降。使用由BET吸附理论和电子跳跃理论预测的水层形成来解释这种行为，对于AFM图案化的SiO ₂表面，即使在相对湿度较低的情况下，也可以预测高水覆盖率。

更新日期：2018-03-20

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