Characterization of RuO2 thin films by Raman spectroscopy

Raman scattering has been used as a technique for the characterization of RuO₂ thin films deposited on different substrates by the metal-organic chemical vapor deposition method and reactive sputtering under various conditions. Red shift and broadening of the linewidth of the Raman peaks are analyzed by the spatial correlation model. The intrinsic linewidth for the RuO₂ films deposited at high and low temperatures has to be adjusted to different values to achieve a good fit for the features. The lineshape and position of the Raman features vary for films deposited on different substrates under the same condition. These differences indicate the existence of stress induced by lattice mismatch and the differential thermal expansion coefficients between RuO₂ and the substrates. After annealing at 650°C in an oxygen atmosphere for 3 h, the linewidth decreases significantly for the RuO₂ thin films deposited at lower temperatures. The results show the improvement of the crystallinity of the films during the annealing process.