Surface is a common scatterer to electron transport. The surface scattering is critical to many applications such as interconnects and sensors. For example, as the demands of microelectronics push for increasingly smaller interconnects, the need for higher electrical conductivity becomes more pronounced.
Copper (Cu), the current standard for interconnect materials, suffers from strong surface scattering that hampers performance.
However, the mechanisms behind this phenomenon, such as which surface orientations cause stronger scattering, have remained unclear. This is partially due to the lack of method that can effectively predict the carrier transport under surface scattering. Existing models all require phenomenological parameters whose values have to be guessed or fitted to available experimental data. This drawback has limited the accuracy and predictive power of these models.
Now this problem is solved by Dr. Yuanyue Liu from the Texas Materials Institute and the Walker Department of Mechanical Engineering, along with his former Ph.D. student Dr. Chenmu Zhang, now a postdoctoral researcher at Rice University. They have developed a parameter-free approach to accurately calculate electron transport in the presence of surface scattering. Their paper, titled “Electron-Surface Scattering from First Principles,” published in ACS Nano. Using this method, they have calculated the electrical conductivity of Cu films with different surface orientations. Their findings challenge long-held beliefs, showing that the (111) surface of Cu is less conductive than the (001) surface—a discovery attributed to the symmetry of the electronic structure. The researchers further propose a novel phenomenological model that better aligns with their first-principles calculations, offering deeper insights and greater predictive capability for systems affected by surface scattering.
The computer code developed in this work can be found at: https://sites.utexas.edu/yuanyue-liu/codes/EDI/
This work is supported by NASA, ONR, and Welch Foundation.
