Many communication and military electronics require field - effect transistors which can operate in the frequency range of 100s of GHz to THz. Graphene is one of the thinnest and strongest known materials with exceptional electronic and thermal properties. The graphene based transistors can exceed the performance of existing transistors which makes them very attractive alternative for next generation high frequency devices. Graphene typically interacts with metals and insulators in its devices which significantly changes its properties. The performance of graphene based devices can be limited by the characteristics of the contact at the metal-graphene interface. It has become imperative to understand the electronic and thermal interaction between graphene and the metals it interfaces in its devices. The thermal and electrical transport across the metal-graphene interfaces is strongly dependent on the structure and nature of the chemical bond at the interface. It is important to decipher the coupled electronic-thermal transport at metal-graphene interfaces as a function of interfacial configuration in order to accurately model the performance of graphene devices and engineer the interfaces when possible. The objective of this research is to develop and employ systematic modeling and experimental techniques that consider the bonding and structure at metal-graphene interfaces in order to investigate the interfacial electrical-thermal transport and elucidate the crucial components of interfacial electrical/thermal contact resistances at time and length scales relevant to nanoscale graphene transistors. A first-principles-based study will be performed to correlate the interfacial thermal characteristics to the nature of chemical bonding and interfacial structure. Metal-graphene interface structures will be fabricated, characterized and thermal/electrical resistances will be measured. This research will lead to development of a new understanding of transport that sets the framework for modeling the performance of next-generation graphene devices with unprecedented accuracy, especially high-frequency and high-power devices.
The understanding of interfacial transport at metal-graphene contact developed by this research will provide directions for efficient thermal management of graphene transistors which will allow them to operate in very high frequency regimes or operate the device at lower temperatures. Such achievement will significantly enhance the capabilities of graphene transistors and reduce a critical barrier for use of these devices in high frequency electronics applications while leading to a significant gain in the energy efficiency, performance, and operating life of future electronic systems. The project will lead to the development of educational materials in the area of Computational Modeling and Energy Transport for both graduate and undergraduate students. Small demonstrations and lectures prepared by this research will increase the awareness of K-12 students for energy related problems and also motivate them for college and graduate education.