Preparation of the SrTiO3 thin films on various substrates using pulsed laser deposition

SrTiO3 (STO) thin films have been prepared on Sapphire(0001), GGG(111), MgO(001), Si(lll), Pt(lll) substrates. The thickness of STO/GGG and STO/Pt are 1500 Angstrom, STO/MgO and STO/Si are 1000 Angstrom, and STO/Sapphire is 400 Angstrom. The chemical composition of film, Sr/Ti was estimated by X-ray Photoelectron Spectroscopy (XPS). STO films on MgO and GGG substrates have the composition closer to the stoichiometric, but STO films on Sapphire, Si, and Pt substrates have the excess Ti composition. The X-ray diffraction (XRD) measurements indicated the STO film was grown epitaxially with (100) orientation on MgO substrates and (111) orientation on Si substrate, but the STO films on Sapphire, GGG, and Pt substrates was grown polycrystalline, which is some kinds of mixed orientation. Scanning electron micrographs reveal that all of the films consist of almost perfect spherical particulates on a smooth background film. The better film morphology (0.1 similar to 0.3 mu m) is obtained using an off-axis arrangement between target and substrate. The reflectance spectra of the STO/MgO film in the TM and TE polarization showed a peak structure near a TO phonon mode (544 cm(-1)) and LO phonon mode (825 cm(-1)).