权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Thin Film Processing of Newly Found, Conductive Transparent Oxides

新发现的导电透明氧化物的薄膜加工

基本信息

批准号：
06555206
负责人：
KAWAZOE Hiroshi
金额：
$ 5.18万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY (1995)Okazaki National Research Institutes (1994)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

Resurlts obatined in the present study are summarized in the following.1) Fabrication of single crystals of n-type conductive oxides with ultra wide band gap. Single crystals of ZnGa_2O_4 spinel and Ga_2O_3, both having band gap larger than 4.5eV and there by transparent in UV region, were successfuly produced by flux method.2)Control of conductivity of ZnGa_2O_4 and Ga_2O_3 single cystals. By exposing the single crystal to reducing atmosphere at a moderate temperature, concentration of oxygen vacancies was controlled arbitrarily. The oxygen vacancy is a donor of electrons. It was experimentally evidenced that the rutile chain which is a linear chain composed by edge sharing of oxygan octahedra is a high way of electrons by estimating Holl mobilities of partialar directions of Ga_2O_3 single cystal.3)Finding of amorphous tranparent and metallic conductive oxides. This type of material fascilitates fabrication of large scale optical waveguides which can transmit electricity simulataneoasly. Glassy, transparent and metallic oxides were found in the CdO rich composition region of CdO-GeO_2 and CdO-PbO_2 systems. Preocessing conditions for fabricating the thin films were optimiged.4)Proposition of working hypotesis for finding p-type conductive wide gap oxides. Most essential problem in this study is how we can modify localized nature of the top of valence band in oxides. In typical oxides the uppermost level of valence band is composed exclusively by O_2p atomic orbitak. Because of low energy of O_2p level, this is almost totally localizing on a single oxygen, and delocalization is not expected. Two different approaches were utilized in the problem : One is selecting the cations with ns^2 lone pair such as Tl^+, Pb^<2+> and Bi^<3+>. Another is selecting nd^<10> closed shell, cations within those cations in which the energy of the filled d band is expected to highest must be selected.

本研究取得的成果总结如下：1)超宽带隙n型导电氧化物单晶的制备。采用熔剂法成功制备了带隙大于4.5eV、在紫外区透明的ZnGa_2O_4尖晶石和Ga_2O_3单晶。2)ZnGa_2O_4和Ga_2O_3单晶电导率的控制。通过将单晶在中等温度下暴露于还原性气氛中，可以任意控制氧空位的浓度。氧空位是电子的供体。通过对Ga_2O_3单晶偏向霍尔迁移率的估计，实验证明金红石链是一种由氧八面体共享棱组成的线性链，是一种高电子方式。3)非晶透明金属导电氧化物的发现。这种类型的材料有利于制造可以同时传输电力的大规模光波导。在CdO-GeO_2和CdO-PbO_2体系的富CdO成分区域中发现了玻璃状、透明的金属氧化物。优化了制备薄膜的工艺条件。4)提出了寻找p型导电宽禁带氧化物的工作假设。这项研究中最重要的问题是我们如何改变氧化物中价带顶部的局部性质。在典型的氧化物中，价带的最高能级仅由O_2p原子轨道组成。由于 O_2p 能级的能量较低，这几乎完全局域于单个氧上，并且不会出现离域。该问题采用了两种不同的方法：一种是选择具有 ns^2 孤对电子的阳离子，例如 Tl^+、Pb^<2+> 和 Bi^<3+>。另一种是选择nd ^ 10 闭合壳层，必须选择那些阳离子中填充的d带的能量预期最高的阳离子。