Optical and Chemical Function Developments for Oxide Semiconductor Device using Substrate of Oriented Zinc Oxide Crystal

采用气相传输法制备了高度取向的氧化锌晶体。氧化锌是一种n型半导体材料，具有宽禁带（3.2eV），在室温下可直接生长。铜氧化锶（SrCu_2O_2）是一种具有宽禁带（3.1eV）的p型半导体材料。本工作采用镜面抛光法制备ZnO衬底，采用PLD法或溅射法制备SrCu_2O_2薄膜。用PLD法制备的p-n结显示出发射紫外光的LED特性。通过使用晶轴取向的ZnO块体，我们可以选择3种表面，Zn-，O-和A-面。Zn面和O面是极性面，A面（平行于c轴）是非极性面。每个面具有不同的结构和电特性。采用O型场效应管，获得了最高的整流特性。测量了该器件的气敏特性。该装置不仅表现出氢和一氧化碳的传感特性，而且还表现出甲苯的传感特性。对甲苯等挥发性有机化合物（VOC）气体的检测表明，该器件由宽禁带半导体氧化物p-n结组成，具有很强的氧化能力。采用ZnSiO_4：Mn薄膜作为发光材料。高电阻率的ZnO具有压电特性。虽然这种器件应该显示出由压电振动调谐的EL特性，但没有获得足够的发光。

Highly oriented zinc oxide crystal was prepared by applying vapor transport method. The oxide semiconductor device was prepared using this crystal as a substrate.Zinc oxide is an n-type semiconductor with wide band gap (3.2 eV). Strontium cupper oxide (SrCu_2O_2) is p-type semiconductor with wide band gap (3.1 eV). In this work, the substrate was prepared by mirror finishing the ZnO crystal, and SrCu_2O_2 thin film was obtained by PLD or sputtering method. The p-n junction prepared by PLD method showed LED characteristic emitting UV light. By using crystal axis oriented ZnO bulk, we can select 3 kinds of surface, Zn-,O- and A-face. The Zn- and the O- faces are polar faces and the A-face (parallel to c-axis) is a non-polar fece. Each face has different characteristic structurally and electrically. Using the O-fece, the highest rectifying characteristic was obtained. The gas sensing property of this device was measured. This device showed the sensing characteristic not only hydrogen and carbon monoxide but also toluene. Detecting the VOC(volatilizing organic compound) gas as toluene indicates the high oxidizing ability of this device composed by p-n junction of semiconducting oxides with the wide band gap.The EL device using ZnO crystal with high resistivity was also prepared. ZnSiO_4:Mn thin film was employed as a luminous. ZnO with high resistivity shows piezo-electric property. Though this device should show the EL property tuned by piezo-electric vibration, the enough luminescence has not been obtained.