Activation Energy Distribution of Dynamical Structural Defects in RuO₂ Films

Sheng-Shiuan Yeh^1,2*, Tsung-Lin Wu¹, Ta-Kang Su¹, Juhn-Jong Lin^1,2,3

¹Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan
²Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu, Taiwan
³Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan

* Presenter:Sheng-Shiuan Yeh, email:yehshengshiuan@gmail.com

In this study, we demonstrate in a series of sputtered RuO₂ polycrystalline films that the 1/f noise originates from fluctuating oxygen vacancies which act as dynamical structural defects. Reducing the amount of oxygen vacancies by adjusting thermal annealing conditions significantly reduces the noise magnitude γ, the Hooge parameter. We quantify the activation energy distribution function, g(E), and calculate the oxygen vacancy density, nTLS, from the measured γ value. We show that g(E) can be explicitly expressed in terms of γ(T) and the electronic parameters of the metal, where T denotes temperature. The inferred nTLS value is in line with the oxygen content determined from the x-ray photoelectron spectroscopy studies. Our method can be applied to determine the g(E) in a wide variety of small metallic devices.

Keywords: RuO₂ Nanowires, Oxygen Vacancies, Two-level Systems, 1/f noise, Activation Energy Distribution