Measuring the thermal conductivity of graphene

0854554 DamesThis award is funded under the American Recovery and Reinvestment Act of 2009（Public Law 111-5）.本研究的目的是对石墨烯的导热性进行首次全面的实验研究，石墨烯是构成石墨的原子级薄的碳片。 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”，伪相对论，量子粒子成为可能。 从应用的角度来看，石墨烯优异的电学和热学性能以及晶圆级加工的前景使其成为改变后硅微电子时代的强有力候选者。 石墨烯预期具有非常高的热导率，大约4000- 5000 W/mK，但直到最近才在使用拉曼光谱的研究中公布了支持这种预期的第一个数据。 本研究的目的是通过实验量化以下基本现象，其中没有一个是以前在石墨烯中测量的：温度的影响，样品的大小和厚度，表面条件，电子与声子的贡献，弹道与扩散传输，和热接触电阻。 智力优势。 将采取三种互补的实验方法：（1）新颖的散热器方法测量沿着封装在介电层之间的石墨烯片的热传递，从而模仿微电子应用并且还产生接触热阻，（2）使用悬浮石墨烯的自加热方法制造和解释简单，但是限于扩散传输，以及（3）微制造传感器方法也基于悬浮石墨烯，并且适用于弹道和扩散传输。这项研究建立在PI现有的合作和初步结果的基础上，以及他们在纳米结构（Dames）和石墨烯沉积和电学测量（Lau）的热测量方面的各自优势。 通过在一个大的参数空间进行实验，预计结果将构成石墨烯热导率的第一个全面的实验研究，从而解决许多相互矛盾的理论预测，这些预测可能不一致高达一个数量级。 为了建立测量的置信度，可以对这些方法进行相互交叉检查，这也将为文献中的初始拉曼测量提供有价值的比较。 实验将详细介绍相关的热性能，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至关重要。 因此，这一新知识有可能改变对原子薄膜中传热的基本理解，这些薄膜的测量方法及其在工业中的应用。 更广泛的影响。 考虑到散热在现代微电子中的巨大重要性，对石墨烯热性能的全面研究将对其在后硅器件技术中的应用至关重要，从而对社会产生广泛的积极影响。 此外，一个综合教育计划将利用加州大学滨江的地位，作为最多样化的加州大学校园和全国领导人在毕业的代表性不足的少数民族。 这项跨学科的研究汇集了物理学和机械工程的本科生和研究生。 研究结果将在期刊、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滨江的夏季物理学院，这是一个针对高中科学教师的研讨会项目：为每位教师提供一个简单的教室工具包，以建立创造性的，人类规模的模拟世界。 每个套件将包括各种纳米材料的文档和百万级代表，包括DNA，碳纳米管和石墨烯，以及缩放的材料样品，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.