EPITAXIAL-GROWTH OF PBTIO3 FILMS ON SRTIO3 BY RF MAGNETRON SPUTTERING

Epitaxial growth of PbTiO3 films on (100)SrTiO3 single crystal plates is investigated in detail for piezoelectric device application. PbTiO3 films are prepared by RF magnetron sputtering at relatively low temperature (200-300-degrees-C) and subsequent annealing. Composition of the sputtered films strongly depends on the sputtering gas (Ar-10%O2) pressure. The films fabricated at about 4 Pa having stoichiometry and a perovskite structure under a wide annealing temperature range. Under these conditions, epitaxial growth of PbTiO3 films on SrTiO3 single crystal is achieved although there is a limitation in the maximum film thickness (< 0.3-mu-m). On the other hand, thicker film (> 0.6-mu-m) is successfully obtained by high temperature (approximately 630-degrees-C) sputtering. Lateral overgrowth of PbTiO3 film is attempted using a high temperature sputtering technique. A TEM micrograph confirms that PbTiO3 film is epitaxially grown on SrTiO3 Single crystal and overgrown laterally to cover Pt electrode film. To characterize film quality, ferroelectric properties are investigated. The dielectric phase transition shows the similarity of the films' characteristics to those of single crystals while the structural phase transition occurs at relatively high temperature. Electromechanical coupling constant k(t) of the PbTiO3 film is evaluated by analyzing impedance characteristics, and is found to be as large as 0.8.