Key Engineering Materials Vols. 421-422

Abstract: The deposition mechanism of metal-Ru films including incubation time was investigated for Ru films prepared by metal organic chemical vapor deposition from (2,4-Dimethylpentadienyl)(ethylcyclopentadienyl)Ruthenium (DER) - O2 system. Substrates with amorphous top-layer having various Hf/Si ratio, SiO2 (native oxide)/(001)Si (SiO2), HfSiON/SiON/(001)Si (HfSiON) and HfO2/SiON/(001)Si (HfO2), were used as substrates. The deposition temperature dependence of the deposition amount at the fixed deposition time ranging from 210 oC to 300 oC revealed that the deposition amount depended on the deposition temperature below 250 oC, while it was almost constant above this temperature. Incubation time depended on the kinds of substrate at 210 oC and the substrate surface was fully covered in a shorter time with smaller deposition amount for the substrates with shorter incubation time. In addition, the film with shorter incubation time had smaller surface roughness.

Abstract: The HfO2 films prepared from alkoxy-derived precursor solution chemically modified with diethanolamine. The effects of UV irradiation on the HfO2 films were investigated. The UV irradiation using low pressure mercury lamp (LPML) was effective for the organics decomposition in the film and densification. The uniform and smooth HfO2 films were obtained. The refractive index of HfO2 films was enhanced.

Abstract: Piezoelectric films using d15 shear-mode can be applied to many useful MEMS devices. The small displacement derived from the d15 shear-mode was directly observed by a SPM measurement. An isolated PZT(52/48) active part having a pair of driving Cu electrodes was processed in a 5 m-thick sputtering film. The displacement measurement of the active part and its FEM analysis suggested that the estimated d15 piezoelectric constant of the film was 590 pm/V. And, the d31 value of the film was -120 pm/V measured by a conventional cantilever method. The obtained piezoelectric constants of the PZT film are near those of bulk.

Abstract: (100)/(001)-oriented PZT thick films were grown on SrRuO3//(100) SrTiO3 and (100) MgO substrates by matel organic chemical vapor deposition (MOCVD) with different volume fraction of (001) orientation, and were compared with (001) single-oriented epitaxial PZT thick films grown on SrRuO3//LaNiO3//(100) CaF2 by polarized Raman spectroscopy. The spectra from (100)-oriented domain and (001)-oriented domain can be individually observed for the films with the mixture orientation of (100)/(001). Raman analysis revealed the different strain state of (100)-oriented and (001)-oriented domains. Moreover, the rotation dependence of A1(1TO) mode could be explained by the calculation using the volume fraction of (001)-oriented domains obtained from X-ray reciprocal space mapping analysis for the films with the mixture orientation of (100)/(001). These results suggest the local structure characterized by Raman spectroscopy almost agreed with the structure characterized by XRD analysis for the films with the mixture orientation of (100)/(001).

Abstract: The effect of poly ammonium acrylate (PAA-NH4) dispersant on the dispersibility of Pb(Zr,Ti)O3 (PZT) slurries and the piezoelectric properties of resultant PZT sintered bodies was investigated for the establishment of environmentally friendly aqueous processing. The dispersion state and viscosity of PAA-NH4-added PZT aqueous slurries strongly depended on the slurry pH. Well-dispersed PZT slurries with negligibly small Pb2+ dissolution were obtained in the alkaline side due to the electrostatic steric hindrance effect of adsorbed polyelectrolyte dispersant molecules with a high dissociation ratio of carboxylic acid groups. The homogeneous dense microstructure and the enhancement of the piezoelectric properties of PZT ceramic bodies were achieved by preparing the aqueous PZT slurry with an optimum amount of dispersant.

Abstract: We have investigated the relationships between the electric field-induced resistance change and the strength of the exchange interaction of the Cr2O3/ La0.7Sr0.3MnO3 (LSMO) magnetic hetero system. The hetero system subjected to field cooling (FC) showed a positive shift in the magnetization curves due to an exchange bias. The exchange bias field changed depending on the FC field. Resulting from the exchange behaviors, the resistance of LSMO film was changed by the application of an electric field to the Cr2O3 gate. This resistance change is more likely due to the interface interaction strength between the Cr2O3 and LSMO film

Abstract: We investigated electrical properties of epitaxial Mn doped bismuth ferrite BiFe0.97Mn0.03O3 (BFMO) thin films with different crystal orientations deposited on Si substrates with appropriate buffer layers. Epitaxial SrRuO3 (SRO) thin films with (001), (101), and (111) orientations were grown on CeO2/yttria-stabilized zirconia (YSZ)/Si(001) substrates and YSZ/Si(001), respectively, by the insertion of MgO and TiO2 atomic layers using pulsed-laser deposition (PLD). Using spin coating, we deposited BFMO thin films onto orientated SRO thin films. The BFMO orientation followed the SRO orientation. The Pr values of the BFMO were ordered as follows {111}>{110}>{100}, which is the same as that predicted by crystallographic considerations. The largest Pr value of the {111} orientation is 76 μC/cm2 at 100 kHz, 25°C.

Abstract: Effect of stacking layers on the structure and properties of Ca(Mg1/3Nb2/3)O3/CaTiO3 (CMN/CT) microwave dielectric heterogeneous thin films prepared was investigated. Precursor solutions for CMN and CT synthesis were obtained by Pechini method. The arrangement pattern has affected structure and properties of heterogeneous thin film. The CMN-CT arrangement heterostructure thin film has second phase from the CMN films layer. The CT-CMN heterostructure film which has a smooth and dense microstructure was composed of pure perovskite phase without any second phase, this result was attributed to the CT film layer which is a buffer layer between substrate and CMN film layer. At 1MHz frequency, CT-CMN exhibits the dielectric properties of εr=47.5, tanδ=0.020.

Abstract: The dc bias and temperature dependence of dielectric properties of Pb1-xBaxZrO3 (PBZ) thin films with higher x (x=0.6, 0.7, 0.8 and 1) were investigated in detail. The results indicated that Pb0.4Ba0.6ZrO3 films possessed a moderate tunability of 32.3% and a higher figure of merit of 53.8, which were measured at 100 kHz and at room temperature. Moreover, Pb0.4Ba0.6ZrO3 films exhibited a smaller temperature coefficient of capacitance TCC-20-90= -1390 ppm/oC.

Abstract: Crystalline ZnO films were grown on Y-stabilized ZrO2 substrates heated at 300 - 600 °C in NH3 atmosphere. It is clarified from Fourier transform infrared measurements that N-doped ZnO films grown at 350 and 400 °C contain N-C and Zn-H bonds. In the devices of n-type ZnO/N-doped ZnO/Au, a good rectification characteristic is attained for an N-doped ZnO film deposited at 300°C, whereas a linear current vs. voltage characteristic is seen for a film deposited at 500 °C.