【作者】 宿磊；

【导师】 姚曼；

【作者基本信息】 大连理工大学 ， 材料物理与化学， 2012， 硕士

【摘要】 砷化镓材料作为Ⅲ-Ⅴ族化合物半导体中最重要、用途最广泛的半导体材料,它具有禁带宽、直接带隙、载流子迁移率高、消耗功率低、抗辐射,耐高温等优点,以其优良的光电特性被广泛应用于微电子和光电子领域。近年来,为了进一步改善砷化镓材料的性能,拓宽其应用领域,进行合理有效的掺杂是目前最常用的途径之一。随着计算材料科学的兴起和快速发展,对掺杂体系进行电子结构和光学性质的理论研究已经成为挖掘GaAs材料应用的重要手段,对发展新型GaAs光电子材料具有极其重要的意义。文中利用基于密度泛函理论框架下的第一性原理平面波赝势方法,对本征闪锌矿GaAs锑(Sb)掺杂GaAs体系和3d过渡金属M(M=Mn,Cr,Fe)掺杂GaAs体系的电子结构和光学性质进行了一系列的研究,主要研究内容如下：首先对本征闪锌矿GaAs的能带结构、态密度和光学性质进行了计算分析,结果表明闪锌矿GaAs是一种直接带隙半导体材料,计算得到的带隙为0.61eV,比实验值1.424eV偏小,这是利用密度泛函理论计算时普遍存在的问题；计算光学性质时,采用“剪刀”算符对带隙进行修正,修正后得到的光学性质结果与实验基本符合,从而验证了计算方法的正确性。随后计算了不同浓度Sb掺杂闪锌矿GaAs体系GaAs1-xSbx (x=0,0.25,0.5,0.75,1)的电子结构和光学性质,包括能带、态密度、复介电函数和吸收系数。计算结果表明：Sb掺杂导致体系晶格常数线性增大,并使得体系导带和价带组成发生改变,禁带宽度呈二次多项式变化。随着掺杂浓度的增加,体系静态介电常数线性增大,吸收带边出现了明显的红移现象,结合电子结构,对掺杂Sb诱发GaAs1-xSbx体系的光学性质改变进行了定性的解释。最后研究了3d过渡金属M(M=Mn,Cr,Fe)掺杂闪锌矿GaAs体系,对体系的磁性、半金属性和光学性质进行了研究和分析。3d过渡金属掺杂之后,由于过渡金属的3d电子与As4p电子的杂化作用,使得体系表现出铁磁性。Mn和Cr掺杂之后,体系表现出明显的半金属性,而Fe掺杂GaAs体系呈现金属性；Mn、Cr掺杂体系的吸收系数在低能端均产生了新的吸收峰,体系的吸收带边基本在同一位置,与本征GaAs相比,出现了明显的红移。对3d过渡金属诱发的磁性和光学性质改变进行了分析,为掺杂闪锌矿GaAs在光电子领域的实际应用提供一定理论依据。更多还原

【Abstract】 GaAs is the most important and the most extensive use Ⅲ-Ⅴ compound semiconductor materials with wide gap, direct band gap, high carrier mobility, low power consumption, radiation resistance, and high temperature resistance. It’s widely applied in the field of microelectronics and optoelectronics because of its excellent optoelectronic characteristics. In recent years, in order to improve its properities and broaden its application field, the reasonable and effective doping is one of the most commonly used methods. With the rapidly development of computational materials science, the theoretical study on electronic and optical properties of doped systems has been an important means. It’s very significant to develop new typical optoelectronic materials.In this paper, the electronic structure and the optical properties of the pure GaAs, Sb-doped GaAs systems and3d transition metals doped GaAs were investigated by using the first-principles pseudopotential approach of the plane wave based on the Density Functional Theory. The main contents are presented as follows:Firstly, we calculate the band structure, density of state and optical properties of the pure zinc blende GaAs. The results indicate that zinc blende GaAs is a direct band gap semiconductor material. The calculation of the band gap0.61eV, compared with the experimental value of1.424eV, has a larger deviation. It’s a common problem existing in the calculations of band gap by DFT method. The calculated band gap is revised by the "scissors" operator and the optical properties obtained after revised agree with the experimental result, which convinced us that our calculation is reliable enough.Afterwards, electronic structure and optical properties of GaAs1-xSbx(x=0,0.25,0.5,0.75,1)have been calculated and the band structure, density of states, complex dielectric function and absorption coefficient have been calculated. The results indicate that Sb doping leads to linearly increasing lattice constants and changing the components of valence and conduction bands of GaAs. The band gap of doped system appears a quadratic polynomial variation tendency. With the increase of the Sb content, the static dielectric constant increased linearly and the absorption wavelength appears an obvious red-shift. The changes of optical properties are qualitatively interpreted in combination with the calculated electronic structure.Finally, the systems of3d transition metals doped GaAs are investigated. The magnetism, half-metallicity and optical properties have been discussed and analysed. By doping3d transition metals in GaAs, the systems show ferromagnetic feature because of the orbital hybrid of3d state of the transition metals and As4p state. The systems of Mn and Cr monodoped GaAs appear obvious half-metallicity, while Fe-doped GaAs shows metallicity. The absorption coefficient of GaAs mono-doped with Mn and Cr produces a new absorption peak at low energy area and the absorption edge are almost in the same position. Comparing with the pure GaAs, the absorption wavelength appears an obvious red-shift. These offer a theoretical basis for the application of doped GaAs in photoelectronics and microelectronics fields.更多还原