Materials Design for Molecular Recognition Devices using Nano-space between tow Oxide Semiconductor Crystals

利用STM系统制备了结构可控的CuO-ZnO“开结”(隧道结)，并讨论了结界面晶轴取向关系对其酒敏性能的影响。CuO-ZnO隧道结即使在室温下也具有大气敏感的电学性质。当选择CuO针尖和氧化锌的极性表面(氧化锌(锌面))作为隧道结时，得到的CuO-氧化锌(锌面)结具有很强的整流特性，而CuO-氧化锌(O面)的整流特性不是很好。只有CuO-ZnO(锌面)隧道结表现出明显的乙醇传感特性。氧化锌的催化活性表面(锌面)对CuO-ZnO隧道结的酒敏特性有重要影响。通过对氧化铜和氧化锌之间的隧道结的电学性质的研究表明，两个晶体之间具有纳米空间的结构良好的“开放界面”将适合于具有分子识别能力的化学传感器元件。

By using the STM system, structurally well-controlled CuO-ZnO "open junction" (tunnel junction) is prepared and the effect of the crystal axis orientation relationship at the junction interface on its alcohol sensing properties is discussed. The CuO-ZnO tunnel junctions have atmosphere sensitive electrical properties even at room temperature. When a CuO tip and Zn-terminated polar surface of ZnO (ZnO (Zn-face)) are chosen for making the tunnel junction, the obtained CuO-ZnO(Zn-face) junction shows highly rectifying characters, where CuO-ZnO(O-face) shows not so good rectifying character. Only the CuO-ZnO(Zn-face) tunnel junction shows a pronounced ethanol sensing characteristics. The catalytic active surface of ZnO(Zn-face) would play an important role for the alcohol sensing characteristics of the CuO-ZnO tunnel junction. Through the current studies on the electrical characterization of the tunnel junction between CuO and ZnO, it is appeared that a structurally well-controlled "open interface" having nano-space between two crystals will be appropriate for the chemical sensor elements, which have an ability of molecular recognition.