Papers by Author: Mi Sook Won

Abstract: Pt/PZT/PbO/Si with the MFIS structure was deposited on the p-type (100) Si substrate by the r.f. magnetron sputtering method with Pb1.1Zr0.53Ti0.47O3 and PbO targets. From the X-ray photoelectron spectroscopy (XPS) results, we could confirm that the partial pressure ratio during PbO deposition affects the interface condition of PbO/Si and the chemical state of Pb existing at the surface of the PZT thin film. The maximum value of the memory window is 3.0 V under the applied voltage of 9V for Pt/PZT (200 nm 400°C)/PbO (80 nm, 300°C)/Si structures with the PbO buffer layer deposited at the partial pressure of 7:3. From these results, we could assume that the PbO buffer layers play a role of the diffusion barrier between the PZT thin film and the Si substrate as well as the seed layer.

Abstract: In this study, ZnO and CuO doped zinc oxide thin films were cathodically deposited in aqueous zinc chloride solutions in the presence of oxygen on a Pt/Ti/SiO2/Si substrate through an electrochemical reaction. A mercurous sulfate electrode was used as a reference electrode and the counter electrode was a Pt spiral wire. Deposition was carried out in solutions containing Zn2+ ions introduced as ZnCl2 salt at concentrations ranging from 5.0 x 10-4 to 5.0 x 10-2 M. The bath temperatures were controlled from 65°C to 80°C. The oxygen gas was introduced from argon/oxygen mixtures allowing its partial pressure to be fixed along with its concentration in the solution. Doping of CuO was carried out in cupric nitrate or a cupric chloride/0.1M KCl solution. The influence of the Cu/Zn concentration, deposition temperature of a solution, applied cathodic potential and deposition time were optimized. After the potential was applied, the cathodic current reached a steady state within 5 min. The composition, and the characterization of the surface of the films were investigated through X-ray diffractometry, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy.

Abstract: The anodic degradation of aqueous phenol and 2-chlorophenol, which are model organic pollutants, has been studied using a flow-through electrochemical cell (FTEC) with carbon fibers as an anode material. For a controlled current electrolysis of an aqueous solution of 2-chlorophenol and phenol, experimental variables, including such as, the current input, the reaction time, and the flow rate of the solutions were considered. The degradation products of the oxidation reactions were identified with HPLC, GC/MS. Small aliphatic acids and CO2 were the main products. Depending on the values of the applied current and reaction time, a complete degradation or the partial oxidation of the compounds to other intermediates was obtained. At the flow rates of 2-6 mL/s were effective on the degradation efficiencies of the 2-chlorophenol and phenol.