Epitaxial BaTiO₃/MgO Structure Grown on GaAs(100) by Pulsed Laser Deposition^*

BaTiO3 thin films on MgO encapsulated GaAs(100) were prepared epitaxially, in condition ranging from 600-degrees-C to 800-degrees-C and from 2 x 10(-4) Torr O2 to 1 X 10(-2) Torr O2, by pulsed laser deposition. The epitaxial relationship between all materials was cube-on-cube. BaTiO3 thin films obtained were c axis oriented tetragonal phase and showed ferroelectric properties. EpitaXial BaTiO3 had quite smooth surface of less than 100 angstrom in roughness. BaTiO3 grown on 40-angstrom-thick epitaxial MgO was also epitaxial although defect density in BaTiO3 looked higher than that in BaTiO3 grown on 400-angstrom-thick MgO. The interfaces of BaTiO3/40-angstrom-thick MgO/GaAs structure were abrupt and free of secondary phases in spite of the quite thin MgO layer.