Static and Time-Resolved Terahertz Measurements of Photoconductivity in Solution-Deposited Ruthenium Oxide Nanofilms
Brian G. Alberding, Paul A. Desario, Adam D. Dunkelberger, Debra R. Rolison, Jeffrey C. Owrutsky, Edwin J. Heilweil
Thin film Ruthenium Oxide (RuO2) is a promising alternative material as a conductive electrode in electronic applications because its rutile crystalline form is metallic and highly conductive. Herein, a previously established solution-deposition multi-layer technique is employed to fabricate ca. 55 nm thick films (nanoskins) and terahertz spectroscopy used to determine their photoconductive properties. Upon calcining at temperatures ranging from 373 K to 773 K, nanoskins undergo a transformation from insulating/semiconductor type behavior to metallic behavior. Terahertz time-domain spectroscopy (THz-TDS) indicates that the nanoskins attain maximum static conductivity when calcined at 673 K. Picosecond time-resolved Terahertz spectroscopy (TRTS) using 400 nm and 800 nm excitation reveals a transition to metallic behavior when calcined at 523 K. For calcine temperatures less than 523 K, the conductivity increases following photoexcitation (del(E) 0) following photoexcitation.