Graphene's (GR) remarkable mechanical and electrical properties - such as its Young's modulus, lowmass per unit area, natural atomic flatness and electrical conductance - would make it an ideal material for micro and nanoelectromechanical systems (MEMS and NEMS). However, the difficulty of attaching GR to supports coupled with naturally occurring internal defects in a few layer GR can significantly adversely affect the performance of such devices. Here, we have used a combined contact resonance atomic force microscopy (CR-AFM) and ultrasonic force microscopy (UFM) approach to characterise and map with nanoscale spatial resolution GR membrane properties inaccessible to most conventional scanning probe characterisation techniques. Using a multi-layer GR plate (membrane) suspended over a round hole we show that this combined approach allows access to the mechanical properties, internal structure and attachment geometry of the membrane providing information about both the supported and suspended regions of the system. We show that UFM allows the precise geometrical position of the supported membrane-substrate contact to be located and provides indication of the local variation of its quality in the contact areas. At the same time, we show that by mapping the position sensitive frequency and phase response of CR-AFM response, one can reliably quantify the membrane stiffness, and image the defects in the suspended area of the membrane. The phase and amplitude of experimental CR-AFM measurements show excellent agreement with an analytical model accounting for the resonance of the combined CR-AFM probe-membrane system. The combination of UFM and CR-AFM provide an beneficial combination for investigation of few-layer NEMS systems based on two dimensional materials.

中文翻译：

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通过接触共振和超声扫描探针显微镜绘制悬浮和支撑多层石墨烯膜的纳米级动态特性

石墨烯 (GR) 卓越的机械和电气性能——例如其杨氏模量、单位面积的低质量、自然原子平坦度和电导率——将使其成为微和纳米机电系统（MEMS 和 NEMS）的理想材料。然而，将 GR 连接到支架上的困难加上几层 GR 中自然发生的内部缺陷，会对此类设备的性能产生显着的不利影响。在这里，我们使用了组合接触共振原子力显微镜 (CR-AFM) 和超声力显微镜 (UFM) 方法来表征和映射大多数传统扫描探针表征技术无法获得的纳米级空间分辨率 GR 膜特性。使用悬挂在圆孔上的多层 GR 板（膜），我们表明这种组合方法允许访问膜的机械性能、内部结构和连接几何形状，提供有关系统支撑和悬挂区域的信息。我们表明 UFM 允许定位受支持的膜 - 基材接触的精确几何位置，并提供接触区域质量局部变化的指示。同时，我们表明，通过映射 CR-AFM 响应的位置敏感频率和相位响应，可以可靠地量化膜刚度，并对膜悬浮区域的缺陷进行成像。实验性 CR-AFM 测量的相位和幅度与解释组合 CR-AFM 探针-膜系统共振的分析模型非常吻合。UFM 和 CR-AFM 的结合为研究基于二维材料的少层 NEMS 系统提供了有益的组合。