| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Wednesday Sessions |
| Session TF+EM+MI-WeA |
| Session: | Thin Film Processes for Electronics and Optics II |
| Presenter: | Robyn Collette, University of Tennessee Knoxville |
| Authors: | R. Collette, University of Tennessee Knoxville Y. Wu, University of Notre Dame J.P. Camden, University of Notre Dame P.D. Rack, University of Tennessee Knoxville |
| Correspondent: | Click to Email |
Surface plasmon resonances can be sustained by metallic nanostructures and have been explored for potential optoelectronic device applications. Superior plasmonic properties may be realized by alloying and consequently tuning the LSPR, however, there has been limited work done on alloys for use in plasmonic devices. The alloy behavior greatly depends on the ordering of the structure; thus, it is crucial to explore how the optical properties are related to the structure of the alloy.
In this work, the structure and optical properties of Au-Al thin film alloys were investigated as both individual metals have strong plasmon resonances. Initially, 350 nm thick AuxAl1-x (0.15<x<0.72) was co-sputtered on 100mm x 15mm silicon substrates. Subsequently samples of 0.9<x<1 and 0<x<0.2 were investigated. Energy dispersive spectroscopy (EDS) was used to measure the composition as a function of position on the substrate for the combinatorial samples. The crystal structure at various compositions were subsequently determined using grazing incidence x-ray diffraction (GIXRD) and the dielectric constants, ε1 and ε2, were determined via spectroscopic ellipsometry. The evolution of phases was studied by annealing various compositions under vacuum and the optical properties were correlated to observed phases on the equilibrium phase diagram. Lastly, we explore the plasmonic properties of lithographically patterned AuxAl1-x (0 <x<0.2). The optical transmission and reflection is measured and compared with electron energy loss spectroscopy results. The phase evolution is studied using a (scanning) transmission electron microscope with an in situ laser heating system and the low loss electron energy loss spectra are correlated to the structural changes. Interestingly, we found in the mixed phase region containing Al and AuAl2 that as the concentration of AuAl2 increased, an increase of ε1 and a decrease of ε2 around 1.5 eV.