We have studied the influence of the thickness and the heat

treatment of the buffer layers and the deposition conditions of the BaTiO3 on the crystallinity, orientation, and morphology of the BaTiO3 films. Methods Buffer layer deposition Polyvinyl pyrrolidone (45% in water) dissolved in 2-propanol is spin-coated onto the silicon substrate as an adhesion layer prior to the buffer layer deposition. Buffer layer solutions are prepared by dissolving lanthanum nitrate hydrate in 2-propanol. The solution is spin-coated on the silicon wafers at 3,000 rpm for 45 s and subjected to a heat treatment at 450°C for 5 min. Lanthanum nitrate hydrate (La(NO3)3) decomposes through nine endothermic weight loss processes with increasing temperature [17]. Between 440°C and 570°C, the lanthanum nitrate hydrate #eFT508 order randurls[1|1|,|CHEM1|]# is decomposed to the intermediate-phase lanthanum oxynitrate (LaONO3). The thickness of the obtained buffer layers in this work ranges between 6 and 10nm as measured with ellipsometry. BaTiO3 thin-film deposition Reagent

grade barium acetate Ba(CH3COO)2 and titanium butoxide Ti(C4H9O)4 are used as precursor materials for barium and titanium, and glacial acetic acid and 2-methoxy ethanol are used as the solvents. The molarity of the solution is 0.25 M. The BTO precursor sol is spin-coated at 3,500 rpm for 45 s, followed by pyrolysis on a hot stage at 350°C to burn out the organic components. This leads to a film thickness of about 30 nm. This process is repeated three or four times LEE011 to obtain a film thickness

around 100 nm. Then, the silicon substrate with the BTO amorphous film is subjected to a high-temperature annealing at 600°C to 750°C for 20 min, with a tube annealing furnace in ambient air. The ramping rates for heating and cooling of the specimen in the annealing system are 100°C/min and −50°C/min, respectively. The process cycle (two or three spin coatings and subsequent high-temperature treatment) is repeated several times to obtain an oriented thin film with a thickness of a few 100 nm. X-ray diffraction measurements The samples are first cleaned with acetone, isopropanol, and de-ionized water. The measurements are carried out with a D8 Discover diffractometer (Bruker Technologies Ltd., Billerica, MA, USA) with CuKα radiation. The diffractograms are L-gulonolactone oxidase recorded for 2θ angles between 15° and 64°, with a step size of 0.004° and time step of 1.2 s. Focused ion beam etching/scanning electron microscopy The cross-section images of the specimens are prepared by a FEI Nova 600 Nanolab dual-beam focused ion beam system (FIB; FEI Co., Hillsboro, OR, USA) and an associated scanning electron microscope (SEM). It allows simultaneous milling and imaging of the specimens. The SEM column is equipped with a high-performance field-emission gun electron source, whereas the FIB system has a gallium liquid metal ion source. Atomic force microscopy The surface roughness of the BTO thin films are measured by atomic force microscopy (AFM) analysis.