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

CuO/ZnO异质结的制备方法是(1)将CuO和ZnO溅射薄膜堆叠或(2)将CuO和ZnO粉末压块烧结。在薄膜CuO/ZnO异质结处观察到高度整流的V-I特性。即使在480K时也能保持较高的整流性能。该结的电容与施加的反向电压无关，表明由于阳离子的相互扩散，在CuO-ZnO界面上产生了p-i-n结构。在高于673K的温度下进行热处理，会破坏整流特性。采用等温电容瞬态光谱（ICTS）对CuO/ZnO薄膜异质结进行了表征，得到了活化能为0.22eV的ICTS信号。除应用于电子器件外，CuO/ZnO异质结还可应用于CO气体传感器和CO氧化催化剂。在CuO-ZnO接触界面上观察到外加电压相关的CO氧化反应。当施加反向偏压（CuO+, ZnO-）时，界面表面CO_2的生成量迅速增加，而施加正向偏压则抑制了界面表面CO_2的生成。这种现象可能是由于CuO表面费米能级位置的变化引起的。为了在CuO/ZnO异质接触器件中增加这种功能，P-i-n结构是必不可少的，它是由Cu^<2+>或Zn^<2+>在接触界面上的相互扩散产生的。为了准确理解CuO/ZnO异质结的电结构，通过评价Cu_xZn_<1-x>O_<1- δ >体系的晶格参数和非化学计量学，研究了Cu^<2+>对ZnO基体的溶解度。根据δ值与x值的关系，可以确定取代溶解Cu在ZnO基体中的溶解度极限，在1000℃时，Cu在ZnO基体中的溶解度约为4.3mol%。

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.