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Fundamental Studies of Development of Quasicrystalline Semiconducting Films

准晶半导体薄膜发展的基础研究

基本信息

批准号：
04402046
负责人：
MIZUTANI Uichiro
金额：
$ 22.21万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04402046/
关键词：
Quasicrystals Approximant Crystals Semiconducting Films 半導体ホール係数電気伝導度

项目摘要

Major results obtained are summarized below.1. The stable composition range of quasicrystalline and approximant phases has been determined in the totally five systems Al-Mg-Zn, Al-Mg-Cu, Al-Mg-Ag, Al-Mg-Pd and Mg-Ga-Zn by using mechanical alloying technique. It is found that the stable quasicrystal is formed when the special condition is fulfillled : the electron concentration is in the range 2.15<e/a<2.20 and the Mg content slightly higher than that of the approximant phase.2. Both RT-and Ml-type quasicrystals have been prepared by liquid quenching technique in the Al-Mg-Zn, Al-Mg-Cu and Al-Mg-Pd and Al-Mg-Pd, Al-Cu-Ru and Al-Pd-Re, respectively. The valence band structure has been studied by XPS, SXS and electronic specific heat measurements. It is found that the valence band structure is described by the free electron picture except for the presence of the pseudogap near the fermi level in the RT-type quasicrystals. The d-band in the Ml-type quasicrystals is widely spread over the valence band energy range and the Al-3p electron distribution is heavily distorted from the free electron-ike one observed in pure Al. As a result, the spiky density of states is sharpened in the Ml-type quasicrystals as compared with the free electron-like RT-type quasicrystals.3. The characteristic features of the valence band structure for Ml- and RT-type quasictystals observed by the above measurements have been reflected in the electron transport properties. The conductivity and electronic specific heat coefficient have been well described by the carrier concentration deduced from the Hall coefficient, regardless of whether Ml-or RT-types are involved. From this we conclude that either electrons or holes dominate at the Femi level in most quasicrystals.4. We could successfully synthesize the Al-Od-Mn thin films by laser abration method.

所获得的主要结果总结如下。用机械合金化技术确定了Al-Mg-Zn、Al-Mg-Cu、Al-Mg-Ag、Al-Mg-Pd和Mg-Ga-Zn五个系统准晶相和近似相的稳定成分范围。研究发现，当电子浓度在2.15<e/a<2.20范围内，Mg含量略高于近似相时，可以形成稳定的准晶.用液相淬火技术分别在Al-Mg-Zn、Al-Mg-Cu、Al-Mg-Pd和Al-Mg-Pd、Al-Cu-Ru、Al-Pd-Re中制备了RT型准晶和ML型准晶。用XPS、SXS和电子比热测量研究了价带结构。研究发现，RT型准晶中除了费米能级附近存在赝能隙外，其价带结构可用自由电子象描述。Ml型准晶的d带在整个价带能量范围内分布很广，Al-3 p电子分布与纯Al中观察到的类自由电子分布相比发生了严重的畸变，因此，与类自由电子RT型准晶相比，Ml型准晶中的尖峰态密度变得尖锐.通过上述测量观察到的Ml型和RT型准晶的价带结构的特征已反映在电子输运性质中。电导率和电子比热系数已经很好地描述了由霍尔系数推导出的载流子浓度，无论是MI型还是RT型。由此我们得出结论，在大多数准电子中，电子或空穴在费米能级上占主导地位。利用激光烧蚀法成功地制备了Al-Od-Mn薄膜。