Electron Phonon Coupling in Superlattice and Multilayer Systems
Abstract
Multilayer thin films are critical to microelectronics design (for example, as diffusion barriers between the silicon active layer and copper interconnects).However, work is needed to understand potential thermal bottlenecks that could arise from their use in transistors. A major source of thermal buildup in microelectronic devices is the interaction between electrons and the surrounding atomic species when they are in a state of thermal nonequilibrium, through electron-phonon (EP) coupling. In this project, we explore EP coupling in multilayer superlattices and oxide conductors. We use ultra-fast optical measurements of these systems, a numerical solution to the two temperature thermal model, and a graded multilayer thermoreflectance model to better understand the relationship between the EP coupling in these multilayer materials and the physical parameters of the system. We show in this project the validity of using a multilayer two temperature model in understanding thermal diffusion on the time and length scales associated with microelectronics, and we show that in superlattice configurations, the electron phonon interactions within the materials can vary greatly as compared to these interactions in the constituent materials. This change in behavior shows dependence on both the thicknesses of the layers within the superlattice and the individual properties of each layer's material. We additionally demonstrate a thorough method of processing thermoreflectance data, accounting for various changes in thermoreectance throughout the multiple layers of the system and depth of energy deposited. A greater understanding of these dynamics within multilayer systems will allow for greater control of the thermal properties as they relate to the design of the system, in turn leading to increased thermal efficiency in microelectronics in the future.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 20, 2019
- Accession Number
- AD1073942
Entities
People
- Andrius V. Bernotas
Organizations
- United States Naval Academy