Residual Stresses in TiO2 Anatase Thin Films Deposited on Glass, Sapphire and Si Substrates

摘要

Anatase-TiOi films (thickness 100-1000 nm) were grown on glass, sapphire,>and Si(100) substrates using pulsed dc-magnetron reactive sputtering. By measuring the curvature of substrates before and after the thin film deposition, the residual stresses were determined. These results clearly show that the bi-axial stresses are compressive type and decreases with the increasing film thickness. The Raman spectra of these films were measured with two different excitation wavelengths (514 and 785 nm) and the thickness dependent shifts of Eg phonon mode were studied. The dominant 144 cm"1 Egmode in TiCh anatase clearly shifts to a higher value by 0.45 to 17.4 cm"1 depending on the type of substrate and the thickness of the film. Maximum shift was seen for the films on glass substrate indicating a higher bi-axial compressive stress in agreement with the curvature measurements. The excitation wavelength dependent shift of Eg mode clearly shows that the bi-axial stress increases along the film depth, being larger at the film/substrate interface.