Laboratory for Energy and Nano-sciences, Masdar Institute of Science and Technology, Abu Dhabi, United Arab Emirates.
Nanotechnology. 2013 Jun 7;24(22):225703. doi: 10.1088/0957-4484/24/22/225703. Epub 2013 May 1.
The need to resolve the electrical properties of confined structures (CNTs, quantum dots, nanorods, etc) is becoming increasingly important in the field of electronic and optoelectronic devices. Here we propose an approach based on amplitude modulated electrostatic force microscopy to obtain measurements at small tip-sample distances, where highly nonlinear forces are present. We discuss how this improves the lateral resolution of the technique and allows probing of the electrical and surface properties. The complete force field at different tip biases is employed to derive the local work function difference. Then, by appropriately biasing the tip-sample system, short-range forces are reconstructed. The short-range component is then separated from the generic tip-sample force in order to recover the pure electrostatic contribution. This data can be employed to derive the tip-sample capacitance curve and the sample dielectric constant. After presenting a theoretical model that justifies the need for probing the electrical properties of the sample in the vicinity of the surface, the methodology is presented in detail and verified experimentally.
解决受限结构（碳纳米管、量子点、纳米棒等）的电学性质的需求在电子和光电设备领域变得越来越重要。在这里，我们提出了一种基于振幅调制静电力显微镜的方法，以在存在高非线性力的小针尖-样品距离下进行测量。我们讨论了这种方法如何提高技术的横向分辨率，并允许探测电和表面性质。利用不同针尖偏压下的完整力场来推导局部功函数差。然后，通过适当偏置针尖-样品系统，重建短程力。然后将短程分量与通用的针尖-样品力分离，以恢复纯静电贡献。这些数据可用于推导针尖-样品电容曲线和样品介电常数。在提出了一个理论模型，证明了需要在表面附近探测样品的电学性质之后，详细介绍了该方法，并进行了实验验证。
