Raman spectroscopy and x-ray diffraction study of PbTiO3 thin films prepared by sol-gel technique

PbTiO3 (PT) thin films were prepared by the sol-gel technique on Si(111) single crystal, fused quartz, and NaCl substrates using two precursor solutions: methanol and 2-methoxyethanol. Raman spectroscopy and x-ray diffraction were used to determine the effects of the precursor solution, substrate, annealing temperature, and film thickness on the film structure and crystallization behavior. The results indicate that the precursor solution plays an important role in the fabrication of pure perovskite PbTiO3 films. The films deposited from methanol solution are able to form the perovskite structure at lower crystallization temperature (similar to 430 degrees C). In contrast, the films deposited from 2-methoxyethanol solution easily form the pyrochlore phase. This is ascribed to the different mechanism of hydrolysis and condensation polymerization of the two precursor solutions. The Raman scattering results on various substrates have significant and interesting differences, especially for the films deposited from 2-methoxyethanol solution. In addition, with increasing the annealing temperature and film thickness, the full width of the Raman peaks at half-maximum decreases and the intensity increases. As to the position of the peaks, most Raman modes of PT films shift to lower frequencies due to the pressure effect in the films. (C) 1999 American Institute of Physics. [S0021-8979(99)04404-7].