Preparation and dielectric properties of YMnO3 ferroelectric thin films bythe sol-gel method

Thin films of YMnO3 are proposed as a new candidate for non-volatile ferroe lectric memory devices. They were prepared via solutions through two differ ent processes: thermal decomposition and reflux using yttrium acetate tetra hydrate and manganese acetate tetrahydrate as starting materials. For coati ngs prepared by thermal decomposition process, the starting materials were dissolved in ethanol containing diethanolamine, and single phase YMnO3 was obtained with heat-treatment at 900 degrees C. When the starting materials were refluxed using 2-ethoxyethanol as a solvent, single phase YMnO3 was ob tained with heat-treatment at 800 degrees C, Scanning electron microscopy s howed that the 300 nm thick films with a stoichiometric Y/Mn ratio had many pinholes, and a very large dielectric loss, 0.83 at 100 kHz. Inclusion of 5-10% excess of Y in the coating solution produced dense structures with im proved dielectric properties. The dielectric constant and loss tangent of t he thin films with Y/Mn ratio of 1.00/0.90 were about 20 and 0.05 at 100 kH z, respectively.