Measuring the thermal conductivity of graphene

该奖项是根据2009年美国复苏和再投资法案(公共法律111-5)资助的。这项研究的目标是对石墨烯的导热系数进行第一次全面的实验研究。石墨烯是构成石墨的原子薄层碳片。关于石墨烯的热方面的兴奋是双重的。从基本的角度来看，石墨烯具有独特的电子色散关系，这使得研究无质量的、伪相对论的量子粒子成为可能。从应用的角度来看，石墨烯卓越的电学和热学性能，以及晶片规模加工的前景，使其成为转变后硅微电子时代的有力候选者。石墨烯有望具有非常高的导热系数，约为4000-5000W/MK，但在使用拉曼光谱的一项研究中，直到最近才公布了第一个支持这一预期的数据。本研究的目的是在实验上量化以下基本现象，这些现象以前从未在石墨烯中测量过：温度、样品大小和厚度、表面条件、电子与声子的贡献、弹道与扩散输运以及接触热阻的影响。智力上的功绩。将采取三种互补的实验方法：(1)一种新颖的热扩散方法，可测量包裹在介质层之间的石墨烯薄膜上的热传递，从而模拟微电子的应用，并产生接触热阻；(2)使用悬浮石墨烯的自加热方法制备和解释简单，但仅限于扩散传输，以及(3)微制造传感器方法，该方法也基于悬浮石墨烯，可同时用于弹道和扩散传输。这项研究建立在PIs现有的合作和初步成果，以及它们在纳米结构热测量(DAMES)和石墨烯沉积和电测量(LAU)方面的各自优势的基础上。通过在大参数空间进行实验，结果有望构成石墨烯导热系数的第一个全面实验研究，从而解决许多相互矛盾的理论预测，这些预测可能会出现高达一个数量级的不一致。为了建立对测量的信心，可以相互交叉检查这些方法，这也将为文献中的初始拉曼测量提供有价值的比较。这些实验将详细说明相关的热性能，包括接触热阻，这对于评估石墨烯在可能的微电子应用中的性能是必不可少的。因此，这一新知识有可能改变对原子薄膜中热传递的基本理解、测量这些薄膜的方法以及它们在工业上的应用。更广泛的影响。考虑到散热在现代微电子中的巨大重要性，全面研究石墨烯的热性质对于其在后硅器件技术中的应用将是至关重要的，从而产生广泛的积极社会影响。此外，一项综合教育计划将利用加州大学河滨分校作为加州大学最多元化校园和全国领先的少数族裔毕业生的地位。这项跨学科的研究汇集了物理和机械工程的本科生和研究生。研究成果将在期刊、会议和课程中广泛传播。更独特的是，研究结果将被纳入加州大学河滨分校的暑期物理学院，这是一个面向高中科学教师的研讨会计划：为每位教师提供一个用于他们课堂的简单工具包，以建立创造性的、人类规模的纳米世界模拟。每个试剂盒都将包括各种纳米材料的文件和百万级表示，包括DNA、碳纳米管和石墨烯，以及按比例缩放的材料样本，以传达石墨烯与铝等传统材料相比的巨大载热能力。

0854554DamesThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The objective of this research is to perform the first comprehensive experimental study of the thermal conductivity of graphene, the atomically-thin sheets of carbon that make up graphite. Excitement regarding thermal aspects of graphene are two-fold. From the fundamental perspective, graphene has a unique electron dispersion relation which enables study of "massless", pseudo-relativistic, quantum particles. From an applications perspective, graphene's superb electrical and thermal properties, and prospects for wafer-scale processing, make it a strong candidate to transform the era of post-silicon microelectronics. Graphene is expected to have very high thermal conductivity, approximately 4000- 5000 W/mK, but only very recently were the first data published to support such expectations, in a study using Raman spectroscopy. The objective of the present research is to experimentally quantify the following essential phenomena, none of which have been measured previously in graphene: the effects of temperature, sample size and thickness, surface conditions, electron vs. phonon contributions, ballistic vs. diffusive transport, and thermal contact resistance. Intellectual Merit. Three complementary experimental approaches will be taken: (1) a novel heat spreader method measures the heat transfer along a graphene sheet encased between dielectric layers, thereby mimicking microelectronics applications and also yielding the thermal contact resistance, (2) a self-heating method using suspended graphene is simple to fabricate and interpret, but is restricted to diffusive transport, and (3) a microfabricated sensors method is also based on suspended graphene, and works for both ballistic and diffusive transport. This research builds on the PIs' existing collaboration and preliminary results, and their respective strengths in thermal measurements of nanostructures (Dames) and graphene deposition and electrical measurements (Lau). By conducting experiments over a large parameter space, the results are expected to constitute the first comprehensive experimental study of graphene's thermal conductivity, thus resolving the many conflicting theoretical predictions which may disagree by up to an order of magnitude. To build confidence in the measurements, the methods can be cross-checked against one another, and this will also provide valuable comparison for the initial Raman measurements in the literature. The experiments will detail the relevant thermal properties, including thermal contact resistance, that are essential to evaluate graphene's performance in possible microelectronics applications. Thus, this new knowledge has the potential to transform the fundamental understanding of heat transfer in atomically-thin films, the ways in which these films are measured, and their applications in industry. Broader Impacts. Considering the tremendous importance of heat dissipation in modern microelectronics, a comprehensive study of graphene's thermal properties will be critical for its application in post-Si device technology, resulting in a broad positive impact to society. Additionally, an integrated education plan will exploit UC Riverside's position as the most diverse UC campus and a national leader in graduating underrepresented minorities. This interdisciplinary research brings together undergraduate and graduate students from Physics and Mechanical Engineering. The research results will be disseminated broadly, in journals, at conferences, and in courses. More uniquely, the results will be incorporated into UC Riverside's Summer Physics Academy, a workshop program for high school science teachers: Each teacher with be provided with a simple kit for their classroom, to build creative, human-scale analogues of the nanoworld. Each kit will include documentation and a million-scale representation of various nanomaterials including DNA, carbon nanotubes, and graphene, as well as scaled material samples to convey the tremendous heat-carrying capacity of graphene as compared to conventional materials like aluminum.