EFRI 2-DARE: Energy Efficient Electronics with Atomic Layers (E3AL)

最近的科学进展已经分离出只有1到3个原子层厚的纳米材料，具有半金属性（如石墨烯）、半导体性（如二硫化钼）和绝缘性（如氮化硼）。与硅等众所周知的大块材料不同，这些原子级薄的材料没有悬垂键，同时在原子层平面上具有很高的导电性和导热性，但在垂直于原子层方向上的导电性非常低。在这个项目中，斯坦福大学的团队（Pop, Goodson, Saraswat, Wong）将利用原子薄材料独特的各向异性特性，在计算机模拟的指导下探索基本测量方法。该团队还将专注于热电测量，这是一个受到较少关注的领域。这项研究的应用可能包括产生很少热量的节能电子产品，以及用于可穿戴传感器和医疗设备的柔性能量采集器。这项工作产生的许多好处和见解也可以应用于传统的电子产品，从而进一步提高国家科学基金会、社会和教育的投资回报。该项目将教育从高中实习生到本科生和研究生研究人员的学生，他们将在斯坦福设计学院接受独特的培训项目。这个项目试图创造一个t形的？工程师（具有纳米技术深度和跨学科横向协作能力）。这种新劳动力的社会影响可能与提议的研究促成的新型纳米科学和纳米技术的社会影响一样重要。研究的技术目标分为五个方面：(1)原子薄材料和器件的建模和仿真，指导其设计和组装。计算探索将支持电学、热学和热电实验。(2)原子层在电子和热电器件中的大规模合成和集成。原子层将组装成具有控制角取向的异构堆栈。(3)检查和改进原子薄材料的电接口，学习如何将它们与外界连接。该团队将利用兴奋剂和表面？和优势?触点，以尽量减少电接触电阻。(4)热学和热电特性。研究人员将检查热界面并探测热导率的动态变化，特别是在原子层的交叉平面方向上。这可以使热二极管和热电器件等应用成为可能。(5)通过将任务#1-4的基本理论和实验联系在一起的方法，使节能设备和电子设备成为可能。该团队将研究利用内置热电效应来转移或操纵热点的晶体管和存储器的可能性，以及用于柔性基板和自然散热受到限制的移动环境的分层热电模块的可能性。这个项目的智力意义的关键部分是它结合了三个学科的专业知识：电气、热/机械和材料工程。团队领导具有在多学科环境中合作和共同指导学生的经验；他们还将建立在指导女性和未被充分代表的少数民族（他们已经在学术界和工业界担任职务）的良好记录上，以及在线教学和学习的良好记录上，包括在nsf赞助的nanoHUB.org上发布的讲座和模拟代码。斯坦福大学的环境非常适合将基础科学进步转化为长期的工业合作伙伴关系，该团队还将与空军研究实验室合作进行热电测量，与桑迪亚国家实验室合作进行原子薄接触，并与IMEC（比利时）和东京大学合作进行材料合成和材料集成的实验方法。

Recent scientific progress has isolated nanomaterials that are only 1 to 3 atomic layers thick, with semi- metallic (e.g. graphene), semiconducting (e.g. molybdenum disulphide) and insulating properties (e.g. boron nitride). Unlike well-known bulk materials such as silicon, these atomically thin materials have no dangling bonds, while possessing high electrical and thermal conductivity in the plane of the atomic layers, yet very low conductivity in the direction perpendicular to the atomic layers. In this project, the Stanford team (Pop, Goodson, Saraswat, Wong) will explore fundamental measurements guided by computer simulations, leveraging the unique anisotropic properties of atomically thin materials. The team will also focus on thermoelectric measurements, an area that has received less attention. Applications of this research could include energy-efficient electronics generating little heat, and flexible energy harvesters for wearable sensors and medical devices. Many of the benefits and insights generated from this work could also be applicable to conventional electronics, thus further improving the return on investment for the National Science Foundation, for society, and for education. The project will educate students from high school interns through undergraduate and graduate researchers, who will be exposed to a unique training program at the Stanford Design School. This program seeks to create ?T-shaped? engineers (with technical depth in nanotechnology and lateral ability to collaborate across disciplines). The societal impact of such a new workforce could be just as important as that of the novel nanoscience and nanotechnology enabled by the proposed research.The technical goals of the research are organized into five tasks: (1) Modeling and simulation of atomically thin materials and devices, guiding their design and assembly. Computational exploration will support the electrical, thermal and thermoelectric experiments. (2) Large scale synthesis and integration of atomic layers into electronic and thermoelectric devices. Atomic layers will be assembled into heterogeneous stacks with controlled angular orientation. (3) Examine and improve electrical inter- faces to atomically thin materials, learning how to connect them to the outside world. The team will leverage doping, and both ?surface? and ?edge? contacts to minimize electrical contact resistance. (4) Thermal and thermoelectric characterization. The researchers will examine thermal interfaces and probe dynamic changes to thermal conductivity, particularly in the cross-plane direction of the atomic layers. These could enable applications like thermal diodes and thermoelectrics. (5) Enable energy- efficient devices and electronics through an approach that ties together the fundamental theory and experiments from Tasks #1-4. The team will examine the possibility of transistors and memory that leverage built-in thermoelectric effects to shift or manipulate hot spots, and that of layered thermoelectric modules for flexible substrates and mobile environments where natural heat sinking is restricted. A key part of the intellectual significance of this project is that it combines expertise from three disciplines: Electrical, Thermal/Mechanical and Materials Engineering. The team leaders have experience collaborating and co-advising students in a multi-disciplinary environment; they will also build on a strong track record of mentoring women and underrepresented minorities (who have gone on to positions in academia and industry) and a strong record of online teaching and learning, including lectures and simulation codes posted on the NSF-sponsored nanoHUB.org. The Stanford environment is uniquely suited for translating fundamental scientific advances to long-term industrial partnerships, and the team will also partner with the Air Force Research Labs for thermoelectric measurements, with Sandia National Labs for atomically thin contacts, and internationally with IMEC (Belgium) and University of Tokyo for material synthesis and experimental approaches for materials integration.