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

表面声光谱为过渡金属二硫化物薄膜提供了新颖、宽带和空间分辨的见解

• 批准号: 1609918
• 负责人: Ludwig Bartels
• 金额: $ 33万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1609918&HistoricalAwards=false
• 关键词: Surface; Acoustic; Spectroscopy; Offers; Novel

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.

非技术描述：当地震撞击时，它会摇动建筑物：能源从地面转移到建筑物，如果建筑物的设计不当 - 他们无法摆脱这种能量并损坏或崩溃。该研究项目使用类似的方法来研究一类称为过渡金属二分法的新型半导体材料。通常，这些材料只是一个原子层厚，并且它们为下一代电子设备提供了巨大的机会，因为它们可以在硅薄的晶体管中使用硅，同时允许光学通信。该方法在表面内使用声波 - 与地震期间摇晃地面的波浪相类似于摇动半导体薄层，并研究它们中的电荷载体如何消散能量。该方法提供了有关电荷载体的动态特性以及它们四处走动的独特知识，以便它们可以维持快速的电子应用。该技术的最大优势在于，它不需要制造电触点或将电线连接到所研究的材料上。由于材料是如此薄，因此电线的金属可以使用更多常规技术对测量结果产生巨大影响。这项研究探讨了将这些材料整合到电子设备中的新型策略。加利福尼亚大学河滨分校是一家西班牙裔服务机构，每个第三名学生都是西班牙裔，其他每个学生都是家庭中第一个上大学的学生。该研究项目由西班牙裔研究生进行，并为UC Riverside的多元化学生团体提供了本科研究机会。技术描述：该研究的重点是研究二维（2D）过渡金属二核代码的运输特性，通过应用表面声波光谱。该方法是无接触式的，并在没有替代方法所需的电气接触引起的任何扰动的情况下提供了对传输属性调制的见解。该方法利用了通过距离研究的薄膜远离毫米远离毫米的跨换能器产生和记录的表面声波。光激发用于在衍射有限的空间分辨率上修改膜的传输特性，该分辨率与当前光致发光和拉曼图的传输特性匹配。这允许对过渡金属二分法膜中传输特性的空间变化的新见解。研究小组探讨了晶界，横向和垂直接口以及其他物质扰动对局部电导率的影响。该项目是跨学科的，结合了加利福尼亚大学河滨分校的准备技术，以及来自德国奥格斯堡大学的国际合作者的专业知识。预计该研究将增强对过渡金属二甲元化膜中载体转运的理解，并具有缺陷，异缘或其他局部变化。获取的知识是设计新设备的设计基础，这些设备结合了功能元素等薄膜的异质界面。