Measurement of Residual Stress in YBa₂Cu₃O_7−x Thin Films by Raman Spectroscopy

In this paper, we reported a different approach to measure residual stress state in YBa₂Cu₃O_7−x (YBCO) films using Raman spectroscopy. YBCO thin films with the thicknesses of approximately 500 nm were synthesized on LaAlO₃ (LAO) and SrTiO₃ (STO) substrates using the Trifluoroacetate-organometallic deposition technology (TFA-MOD). A linear relationship was observed between the Raman peak shift and residual stress. Moreover, it was noted that, as for free-standing YBCO and YBCO thin film, a linear relationship was obtained between the Raman peak shift Δ ω, the residual stress σ, and the stress factor k = 179.3 (cm Mpa), i.e., σ=179.3×Δω(Mpa). It is found that this method allowed the residual stress of YBCO thin films to be directly measured using the Raman shift factor. This test method can be used for the rapid and non-destructive detection of residual stress in YBCO films.