Hydrodynamic Electron Transport in 2-Dimensional Materials for Nanoelectronics
Abstract
In this project, we investigate hydrodynamic electron transport in 2-dimensional (2D) materials and develop RF-to-THz devices that engineer hydrodynamic wave modes. To this end, we create van der Waals (vdW) heterostructures based on monolayer and bilayer graphene, 2D superconductors, and atomically thin hexagonal boron nitride (hBN). The graphene and 2D superconductors serve as 2D hydrodynamic transport media, while the hBN is used as tunneling barriers or dielectric separators between the 2D hydrodynamic media. In order to improve the vdW sample quality, we prepare samples and fabricate devices in an inert, ultra-high vacuum environment to prevent degradation of the surfaces and interfaces. Hydrodynamic transport is characterized at both DC and high frequencies. The dispersion relation of hydrodynamic wave modes are engineered by controlling the range of the Coulomb interactions of 2D electrons via top gates proximate to the 2D channels. Furthermore, by putting together two or more atomic layers to form vertically stacked heterostructures, we utilize both Coulomb drag and other electromagnetic interactions between the two layers, which add another means to manipulate the hydrodynamic wave modes. The ultimate goal of the research is studying the nonlinearity and instability of hydrodynamic waves in 2D materials, in order to realize novel RF and THz devices. Specific aims of the research are: (i) measurement of thermodynamic and transport parameters of the hydrodynamic process, such as electronic entropy, thermal conductivity, and viscosity; (ii) demonstration of hydrodynamic convective flow in graphene and other 2D materials; (iii) development of layered 2D RF and THz devices that can potentially generate gain via wave-current and wave-particle interactions (such as two-stream instabilities) or that can create electron density shock waves and solitons; (iv) demonstration of THz Josephson Cooper pair density wave devices based on 2D superconductors.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 15, 2018
- Source ID
- W911NF1710574
Entities
People
- Philip Kim
Organizations
- Army Contracting Command
- Harvard University
- United States Army