Ultra-thin lead titanate films grown by molecular beam epitaxy

The growth of atomically-flat thin films of ferroelectric PbTiO3 on SrTiO3 substrates, using molecular beam epitaxy, is reported. The main issue in the growth of these materials is the high volatility of lead. This can be largely overcome by using PbO, instead of Pb, as a source and by using atomic oxygen during growth. The continuous decrease of the out-of-plane lattice parameter with increasing temperature in the investigated range (RT-650 degrees C), indicates that the films are still ferroelectric at the growth temperature (T-g = 600 degrees C), as expected according to the theoretical prediction of T-C = 765 degrees C (compared to T-C(bulk) = 490 degrees C) for the present mismatch strain values.