Materials Design of Electronic Devices Using Heat-Stable Metal-Oxide Semiconductor junction

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The CuO/ZnO heterojunctions are fabricated by (1) stacking of CuO and ZnO sputtered thin-film or (2) sintering stacked CuO and ZnO powder compacts. Highly rectifying V-I characteristics is observed at thin-film CuO/ZnO heterojunction. Rectifying character kept at higher temperature even at 480K.Capacitance of the junction is independent of applied reverse voltage and it would indicate that a p-i-n structure is produced at CuO-ZnO interface due to the inter diffusion of the cations. The rectifying character is broken by the thermal treated at higher than 673K.Isothermal capacitance transient spectroscopy (ICTS) is applied for the characterization of the junctions and the ICTS signals whose activation energy of 0.22eV is observed at the thermal treated thin film CuO/ZnO heterojunction.Except for the application to the electronic devices, the CuO/ZnO heterojunction can also be applied to the CO gas sensor and catalysts for CO oxidation. Applied voltage dependent CO oxidation reaction is observed at the CuO-ZnO contact interface. When revese bias (CuO+, ZnO-) is applied, the amount of produced CO_2 from the catalytic surface of interface rapidly enhanced, where it suppressed by applying forward bias. The phenomenon would be due to the variation in Fermi level position of CuO surface. For the addition of such a function to the CuO/ZnO heterocontact device, P-i-n structure is indispensable and it is produced by the inter diffusion of Cu^<2+> or Zn^<2+> at the contact interface. For the precise understanding of the electric structure of the CuO/ZnO heterojunction, solubility of Cu^<2+> to ZnO matrix is investigated by evaluating the lattice parameters and non-stoichiometry of the Cu_xZn_<1-x>O_<1-delta> systems. By the relation of the value of delta and x, the solubility limit of substitutionally solved Cu into ZnO matrix is able to be evaluated and it was about 4.3mol% at 1000ﾟC.