Surface Acoustic Spectroscopy Offers Novel, Broadband, and Spatially-Resolved Insight into Transition Metal Dichalcogenides Films

非技术描述：当地震发生时，它会震动建筑物：能量从地面转移到建筑物上，如果建筑物设计不当，它们就无法摆脱这种能量，从而受损或倒塌。该研究项目使用类似的方法来研究一类特殊的新型半导体材料，称为过渡金属二硫属化物。通常，这些材料只有一个原子层厚，它们为下一代电子器件提供了巨大的机会，因为它们可以在晶体管中以硅无法达到的厚度提供服务，同时允许光通信。这种方法使用表面内的声波--与地震时震动地面的声波非常相似--来摇动半导体薄层，并研究其中的电荷载流子如何耗散能量。该方法提供了关于电荷载流子的动态特性以及它们如何自由移动的独特知识，以便它们能够维持快速的电子应用。这种技术的最大优点是它不需要制造电接触或将电线连接到正在研究的材料上。由于材料非常薄，金属丝可能会对使用更传统技术的测量结果产生巨大影响。这项研究探索了将这些材料集成到电子设备中的新策略。位于滨江的加州大学是一所西班牙裔服务机构，每三名学生中就有一名是西班牙裔，每三名学生中就有一名是家庭中第一个上大学的学生。本研究项目是由一名西班牙裔研究生进行的，为加州大学滨江分校的多元化学生提供了本科生研究的机会。技术说明：本研究的重点是通过应用表面声波光谱研究二维（2D）过渡金属二硫属化物的输运性质。该方法是非接触式的，并提供了深入了解的传输特性调制的情况下，所需的替代方法的电接触引起的任何扰动。该方法利用表面声波产生和记录的叉指换能器，间隔毫米远离调查中的电影。光激发是用来修改在衍射限制的空间分辨率媲美当前的光致发光和拉曼地图的膜的传输特性。这使得新的洞察过渡金属二硫属化物薄膜中的传输特性的空间变化。研究小组探索了晶界、横向和垂直界面以及其他材料扰动对局部电导率的影响。该项目是跨学科的，将加州大学滨江分校的制备技术与德国奥格斯堡大学的国际合作者的专业知识相结合。该研究有望增强对过渡金属二硫属化物薄膜中载流子输运的理解，包括缺陷、异质结或其他局部变化。所获得的知识是一个新的设备，将异质结的功能元件，这样的电影设计的基础。

Non-technical Description: When an earthquake hits it shakes the buildings: energy is transferred from the ground to the buildings and - if the buildings are not designed appropriately - they cannot get rid of that energy and become damaged or collapsed. This research project uses a similar approach to study a particular class of novel semiconducting materials called transition metal dichalcogenides. Usually, these materials are only a single atomic layer thick and they hold tremendous opportunity for next generation electronic devices, because they can serve in a transistor at a thinness unattainable by silicon while at the same time allowing for optical communication. This method uses sound waves within surfaces - waves much akin to those that shake the ground during earthquakes - to rock the semiconductor thin layers and to study how the charge carriers in them dissipate the energy. The approach provides unique knowledge about the dynamic properties of charge carriers and how free they are to move around so that they can sustain fast electronic applications. The great advantage of this technique is that it does not require fabrication of electrical contacts or attaching wires to the material under investigation. Because the material is so thin, the metal of the wires can have a huge impact on the results of measurements using more conventional techniques. This research explores novel strategies for the integration of these materials into electronic devices. The University of California at Riverside is a Hispanic serving institution with every third student being Hispanic and every other student being the first in the family to attend college. This research project is conducted by a Hispanic graduate student and offers undergraduate research opportunity to UC Riverside's diverse student body.Technical Description: This research is focused on studying the transport properties of two-dimensional (2D) transition metal dichalcogenides by applying surface acoustic wave spectroscopy. The method is contactless and provides insight into the transport properties modulations in absence of any perturbation caused by electrical contacts needed for alternative methods. The approach utilizes surface acoustic waves generated and recorded by means of interdigital transducers that are spaced millimeters away from the films under investigation. Optical excitation is used to modify the transport properties of the films at diffraction-limited spatial resolution rivaling that of current photoluminescence and Raman maps. This allows new insight into the spatial variation of transport properties in transition metal dichalcogenide films. The research team explores the impact of grain boundaries, lateral and vertical interfaces, and other material perturbations on the local conductivity. The project is interdisciplinary, combining the preparative techniques available at the University of California, Riverside, with the expertise of an international collaborator from University of Augsburg, Germany. The research is expected to enhance the understanding of carrier transport in transition metal dichalcogenide films with defects, heterojunctions or other local variations. The acquired knowledge is a foundation for design of novel devices that incorporate heterojunctions of such films as functional elements.