@article{zohni_buckner_kim_kingon_maranchi_siergiej_2008, title={Effects of adhesion layers on the ferroelectric properties of lead zirconium titanate thin films deposited on silicon nitride coated silicon substrates}, volume={516}, ISSN={["0040-6090"]}, DOI={10.1016/j.tsf.2007.10.130}, abstractNote={We have investigated the addition of silicon nitride (Si3N4) thin films into sol–gel deposited lead zirconium titanate (PZT) stacks and quantified the effects of various adhesion layers on the ferroelectric characteristics of these stacks. Although previous research has investigated issues related to the adhesion characteristics of PZT films, this research considers four specific adhesion layers deposited onto a silicon nitride coated substrate: zirconium (Zr), zirconium dioxide (ZrO2), titanium (Ti) and tantalum (Ta), and compares experimental characteristics of each. Adhesion layer thicknesses of 15 nm and 25 nm were tested with pyrolysis temperatures of 600 °C and 650 °C. For many of the adhesion layers, the remnant polarization Pr and capacitance–voltage (C–V) characteristics are similar to conventional PZT stacks deposited onto silicon dioxide (SiO2) coated substrates, but only Ta withstands the thermal processing required for PZT deposition.}, number={18}, journal={THIN SOLID FILMS}, author={Zohni, Omar and Buckner, Gregory and Kim, Taeyun and Kingon, Angus and Maranchi, Jeff and Siergiej, Richard}, year={2008}, month={Jul}, pages={6052–6057} }
 @article{zohni_buckner_kim_kingon_maranchi_siergiej_2007, title={Investigating thin film stresses in stacked silicon dioxide/silicon nitride structures and quantifying their effects on frequency response}, volume={17}, ISSN={["0960-1317"]}, DOI={10.1088/0960-1317/17/5/026}, abstractNote={We have investigated the frequency shift caused by thin film stresses in silicon nitride (Si3N4) and silicon dioxide (SiO2) layers used during the fabrication of lead zirconium titanate (PZT) microelectromechanical (MEMS) devices. The films are deposited via thermal oxidation and low pressure chemical vapor deposition onto bare silicon wafers. Although previous research has reported stresses in these films, this paper introduces approaches to measure, model and predict the effects of these stresses on the frequency response of MEMS devices. Thin film stresses in each layer of a PZT stack are measured using a curvature measurement system, and these measurements are correlated to finite element analysis results and experimental vibration data. These comparisons illustrate the significance of the thin film stresses and their effect on the mechanical behavior of MEMS devices, in particular that as the membrane structures get thinner the frequency shift becomes much larger.}, number={5}, journal={JOURNAL OF MICROMECHANICS AND MICROENGINEERING}, author={Zohni, Omar and Buckner, Gregory and Kim, Taeyun and Kingon, Angus and Maranchi, Jeff and Siergiej, Richard}, year={2007}, month={May}, pages={1042–1051} }
 @article{kim_kingon_maria_croswell_2007, title={Lead zirconate titanate thin film capacitors on electroless nickel coated copper foils for embedded passive applications}, volume={515}, ISSN={["0040-6090"]}, DOI={10.1016/j.tsf.2007.02.085}, abstractNote={Lead zirconate titanate (PZT, 52/48) thin film capacitors were prepared on electroless Ni coated Cu foil by chemical solution deposition for printed wiring board embedded capacitor applications. Phase development, dielectric properties, and leakage characteristics of capacitors were investigated, in particular as a function of the process temperature. Dielectric properties of the capacitors were dependent on the crystallization temperature, and capacitance densities of more than 350 nF/cm2 and loss tangent of less than 0.03 were measured for capacitors crystallized below 600 °C. Lowest leakage current densities (around 2 × 10− 7 A/cm2 at 10 V direct current (DC)) and highest breakdown fields could be obtained for capacitors crystallized at 650 °C. Capacitors with different thickness and a two-layer capacitor model were used in analyzing the interface layer between PZT and the underlying electroless Ni. From the capacitance and leakage measurements, it is suggested that the interface reaction layer has low permittivity (K around 30) and high defect concentration, which has an important effect on the electrical properties of capacitors. This interface is from the reaction of the electroless nickel layer with the adjacent PZT, and may specifically be moderated by the nickel phosphide (Ni–P) phase, transformed from amorphous Ni during the annealing step. The results have significant implications for embedded capacitors in printed wiring boards. They demonstrate that the process can be tuned to produce either voltage independent capacitors with low leakage and high breakdown fields (above 30 V DC), or the more usual hysteretic, switching, ferroelectric capacitors with higher capacitance densities.}, number={18}, journal={THIN SOLID FILMS}, author={Kim, Taeyun and Kingon, Angus I. and Maria, Jon-Paul and Croswell, Robert T.}, year={2007}, month={Jun}, pages={7331–7336} }
 @article{kim_kingon_maria_croswell_2006, title={Electrical properties of lead zirconate titanate thin films with a ZrO2 buffer layer on an electroless Ni-coated Cu foil}, volume={89}, ISSN={["1551-2916"]}, DOI={10.1111/j.1551-2916.2006.01240.x}, abstractNote={ The effect of zirconia (ZrO2) buffer layers on the phase development and electrical properties of lead zirconate titanate (PZT, 52/48) capacitors on an electroless Ni (P)‐coated Cu foil was investigated. It was demonstrated that the buffer layer can be used to engineer the final properties. The incorporation of the ZrO2 buffer layers retained acceptable capacitance densities (>350 nF/cm2 for 50 nm thick ZrO2), while significantly reducing leakage currents and improving reliability (<10−7 A/cm2 after 1 h at 25 VDC for 100 nm thick ZrO2), compared with PZT thin films directly on electroless Ni (P). The results are particularly important for embedded capacitor applications. }, number={11}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Kim, Taeyun and Kingon, Angus I. and Maria, Jon-Paul and Croswell, Robert T.}, year={2006}, month={Nov}, pages={3426–3430} }
 @article{kim_hanson_gruverman_kingon_streiffer_2006, title={Ferroelectric behavior in nominally relaxor lead lanthanum zirconate titanate thin films prepared by chemical solution deposition on copper foil}, volume={88}, number={26}, journal={Applied Physics Letters}, author={Kim, T. and Hanson, J. N. and Gruverman, A. and Kingon, A. I. and Streiffer, S. K.}, year={2006} }
 @article{kim_kingon_maria_croswell_2004, title={Ca-doped lead zirconate titanate thin film capacitors on base metal nickel on copper foil}, volume={19}, ISSN={["0884-2914"]}, DOI={10.1557/jmr.2004.0387}, abstractNote={Ca-doped lead zirconate titanate (52/48) thin film capacitors were prepared on electroless nickel-coated copper foils for embedded capacitor applications. The impact of Ca doping and process parameter variations was studied. Ca addition significantly reduced the temperature coefficient of capacitance. Specifically, the temperature variation was reduced to less than 10% between 300 and 580 K through calcium addition. Optimized capacitance densities and loss tangents were 400 nF/cm2 and 0.02, respectively. Crystallization temperatures of 600 °C yielded these optimized electrical properties, while higher temperatures resulted in interfacial reactions. The influence of oxygen partial pressure during crystallization was also studied. Dielectric properties were sensitive to pO2, with optimal properties occurring in a narrow pO2 window centered about 10−3 Torr. The trends with oxygen pressure were mirrored by changes in phase assemblage. Electrical transport across the dielectric layers was not strongly dependent upon doping level. This insensitivity was attributed to a thin interfacial layer present in all samples. Interface analysis using equivalent circuit analogues showed the nature of the interface to be highly resistive (insulating), rather than semiconducting or conducting.}, number={10}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Kim, T and Kingon, AI and Maria, JP and Croswell, RT}, year={2004}, month={Oct}, pages={2841–2848} }