EFFECTS OF SUBSTRATE SURFACE ROUGHNESS ON ELECTRON-PHONON COUPLING IN THIN AU FILMS

摘要

As device fabrication and design engineers continue to decrease the sizes of transistors within integrated circuits, the removal of waste heat becomes a limiting factor that impedes further advances in solid state nanotechnology. An in-depth understanding of how heat is transferred in thin metal films is critical to the design of better methods of heat transport in microelectronic applications. This work examines how electron scattering processes in thin Au films is affected by the presence of a dielectric interface. Ten Au films are deposited on Si and glass substrates subject to different fabrication conditions, causing a varying degree of "roughness" between the film and the substrate. The Au samples are subjected to nonequilibrium heating via the femtosecond pulsed transient thermoreflectance (TTR) technique. The rate of electron-phonon equilibration is examined by comparing the temperature decay on the surface of the Au film to the two temperature model (TTM) with insulative boundary conditions.