Browsing by Author "Hahn, Byung-Dong"

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    Enhanced domain contribution to ferroelectric properties in freestanding thick films
    Ryu, Jungho; Priya, Shashank; Park, Chee-Sung; Kim, Kun-Young; Choi, Jong-Jin; Hahn, Byung-Dong; Yoon, Woon-Ha; Lee, Byoung-Kuk; Park, Dong-Soo; Park, Chan (American Institute of Physics, 2009-07-15)
    We report the success in fabricating clamped, "island," and freestanding 10 mu m thick piezoelectric films using aerosol deposition. The deposition was conducted at room temperature by impinging the piezoelectric particles flowing through the nozzle onto platinized silicon (Pt/Ti/SiO(2)/Si) substrate and crystallization was conducted by annealing at 700 degrees C. Freestanding films were synthesized by increasing the cooling rate from annealing temperature to room temperature which resulted in large internal stress between the substrate and film interface. Dielectric and ferroelectric characterizations showed enhanced ferroelectric performance of freestanding films as compared to continuous or clamped film which was associated to increased domain contribution due to decrease in degree of clamping as further confirmed by piezoforce microscopy. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3181058]
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    Stress-controlled Pb(Zr0.52Ti0.48)O-3 thick films by thermal expansion mismatch between substrate and Pb(Zr0.52Ti0.48)O-3 film
    Han, Guifang; Ryu, Jungho; Yoon, Woon-Ha; Choi, Jong-Jin; Hahn, Byung-Dong; Kim, Jong-Woo; Park, Dong-Soo; Ahn, Cheol-Woo; Priya, Shashank; Jeong, Dae-Yong (American Institute of Physics, 2011-12-15)
    Polycrystalline Pb(Zr0.52Ti0.48)O-3 (PZT) thick films (thickness similar to 10 mu m) were successfully fabricated by using a novel aerosol deposition technique on Si wafer, sapphire, and single crystal yitria stabilized zirconia (YSZ) wafer substrates with Pt electrodes and their dielectric, ferroelectric, and piezoelectric properties, and in-plane stresses were investigated. The films with different stress conditions were simply controlled by the coefficient of thermal expansion (CTE) misfit of PZT films and substrates. The results showed that the films bearing in-plane compressive stress deposited on the YSZ and sapphire substrates have superior dielectric, ferroelectric (similar to 90%), and piezoelectric (>200%) properties over that of the Si wafer. Among these three substrates, YSZ shows superior properties of the PZT films. However, films on Si wafer with tensile stress present lower properties. We believed that in-plane compressive stresses within the films are benefited, the formation of c-domain parallel to the thickness direction resulting in the higher piezoelectric properties. These results suggest that the properties of polycrystalline PZT thick films can be adjusted by simply choosing the substrates with different CTEs. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3669384]