In-situ Transmission Electron Microscopy Studies of Metal Contact with InGaAs Nanochannels: Correlating Interface Reactions with Properties

非技术描述：这项研究项目侧重于在纳米尺度上对金属-半导体反应的基本理解和控制的发展。研究小组利用透射电子显微镜(TEM)在原子尺度上实时研究这些纳米材料的结构、性能和功能之间的关系，这些材料类似于一种新型纳米晶体管的工作条件。这项研究有望为金属-半导体界面及其反应的基础材料科学提供新的见解，这一领域对于开发先进的III-V化合物半导体晶体管沟道的金属接触具有重要的技术意义。外展和教育活动与研究活动很好地结合在一起，包括(1)在当前的研究生和本科课程中开发半导体异质结构和微制造多学科领域的新部门，以及(2)通过加州大学圣地亚哥分校的各种外展活动让高中生和本科生参与动手研究，特别强调纳入代表不足的群体。技术描述：在这个研究项目中，Pi和他的团队利用一种新型的透射电子显微镜(TEM)测量方法来原位监测金属与III-V半导体接触的反应。利用镍硅化将III-V半导体的翅片键合到硅电子显微镜栅格上，形成独立的纳米级异质结构(即纳米沟道)，用于原位加热研究和非原位电学测量。具有不同沟道宽度、III-V晶体取向和表面形貌的多个纳米通道可以集成在同一个TEM网格上，用于原位和非原位相结合的研究。利用这一能力，该团队将所产生的纳米沟道组成、界面结构和晶体管性能与III-V翅片尺寸、晶体取向和应力的影响相关联。特别是，这项研究工作允许对Ni和InGaAs之间的合金形成作为尺寸和晶体取向的函数的实验，并解决了以下科学问题：(I)III-V翅片尺寸对所形成的NiInGaAs合金的结构和成分的影响，(Ii)界面和应变工程对超短沟道中Ni-InGaAs反应和形核的影响，以及(Iii)多层接触堆栈中有限的Ni扩散源对合金成分和结构的影响。这一发现对于开发亚10纳米III-V化合物半导体晶体管沟道的欧姆接触具有重要意义。纳米沟道结构在电子显微镜网格上的晶片键合可用于结合原位电子显微镜和异地电学研究，这可能使在其他材料系统中进行基础界面研究成为可能。

Non-Technical Description: This research project focuses on the development of fundamental understanding and control of metal-semiconductor reactions at nanoscale. The research team utilizes transmission electron microscopy (TEM) to study, at the atomic scale and in real time, the relationship between structure, properties, and functionality of these nanoscale materials similar to the working conditions of a new class of nanoscale transistors. The research is expected to provide new insights into the fundamental materials science on the metal-semiconductor interface and their reactions, an area of technological importance for developing metal contacts for advanced III-V compound semiconductor transistor channels. The outreach and educational activities are well integrated with the research activities and include (1) developing new sections in current graduate and undergraduate courses in the multidisciplinary area of semiconductor heterostructures and microfabrication, and (2) involving high-school and undergraduate students in hands-on research through various outreach activities at UC San Diego, with a particular emphasis on the inclusion of underrepresented groups.Technical Description: In this research project, the PI and his team utilize a novel transmission electron microscopy (TEM) measurement method to monitor, in-situ, reactions of metal contact with III-V semiconductors. Fins of III-V semiconductors are wafer bonded to a Si TEM grid using Ni silicidation to form free-standing nanoscale heterostructures (i.e., nanochannels) for both in-situ heating study and ex-situ electrical measurements. Multiple nanochannels designed with various channel widths, III-V crystallographic orientations, and surface morphologies, can be integrated on the same TEM grid for the combined in-situ and ex-situ studies. With this capability, the team correlates the resulted nanochannel composition, interface structure and the transistor performance with the effects of III-V fin size, crystallographic orientation and stress. In particular, the research work allows experiments on alloy formation between Ni and InGaAs as a function of size and crystal orientation and addresses the following scientific questions: (i) the III-V fin size effects on the structure and composition of the formed NiInGaAs alloys, (ii) the influence of interfaces and strain engineering on the Ni-InGaAs reaction and nucleation in ultra-short channels, and (iii) the effect of a limited Ni diffusion source in a multi-layered contact stack on the alloy composition and structure. The findings are important for developing Ohmic contacts for sub-10 nanometer III-V compound semiconductor transistor channels. The wafer bonding of nanochannel structures on TEM grid for the combined in-situ TEM and ex-situ electrical study can potentially enable fundamental interface studies in other materials systems.