半导体中光学声子形变势的第一原理计算

学位：理学硕士院系专业：物理与机电工程学院物理学系_半导体物理与器件学号：YL00003

Valence-Band Offset at Si-GaAs(001) Interface and Its Strain-Induced Effects

【中文摘要】 本文应用平均键能理化和形变势方法对理想的Ｓｉ－ＧａＡｓ（００１）异质界面的价带不连续性进行了理论确定，全面分析了应变的静流体分量和单轴分量所起的作用，以及阳离子浅ｄ轨道的影响．得出了Ｓｉ－ＧａＡｓ（００１）系统的各价带能量不连续值与弹性应变的定量关系，并对结果进行了讨论． 【英文摘要】 Abstract This paper reports a theoretical determination of the valence-band offset at strained heterojunction Si-GaAs(001 )under idea situation combining the average bond energy theory and deformation potential method. The effect of the shallow d-orbitals in Ga atom on the valence-band offset is discussed. It is found that the offsets between the average valence-band energies and between the heavy hole bands are less affected by the elastic strain, however, the offsets between the topmost valence-band sta...福建省自然科学基金,国家自然科学基

Exceeding Strain-induced Effects on the Electronic Properties of InAs/GaAs Strained-layer Superlattices

【中文摘要】 建议用一种基于超晶格自洽超原胞计算的形变势方法来确定ＩｎＡｓ／ＧａＡｓ应变异质界面的能带排列情况。该方法全面考虑了界面电荷、弹性应变以及自旋－轨道耦合等因素对能带排列的影响。结果表明，ＩｎＡｓ／ＧａＡｓ异质界面的能带排列具有极端显著的应变效应，通过人工控制其平面内晶格常数（可由选择不同的衬底来实现），可使其成为Ⅰ型，Ⅱ型超晶格或金属。此应变效应主要来源于单轴应力及其与自旋－轨道分裂的耦合，而流体静压和界面电荷的作用则相对很小．本文对以ＧａＡｓ为衬底情况下的计算结果与Ｘ射线光发射实验数据相一致。 【英文摘要】 A theoretical method called selfconsistent deformation potential method issuggested to detemine the band lineup at InAs/GaAs heterointerfaces under different strain con-ditions. It is shown that the InAs/GaAs system has a exceeding strain effect on its electronicproperties, and can be modulated to become a type Ⅰ or type Ⅱ superlattice or a metal by control-ling artificially its shain condition. The exceeding strain effect is mainly due to the uniaxis stressand its interaction with the spin-orbit splitting,...福建省自然科学基

Self-consistent Virtual Crystal Calculation of Electronic Structure for Al_xGa_(1-x)As Alloy

【中文摘要】 对于包含芯态的全电子势的ＬＭＴＯ－ＡＳＡ能带计算方法，建议用一种虚晶近似的合金能带计算方法（ＬＭＴＯ－ＡＳＡ－ＶＣＡ），文中着重研究该方法的能带自洽迭代计算方案，在Ａｌ＿ｘＧａ＿（１－ｘ）Ａｓ合金能带计算中获得合理的虚晶近似的能带结构。 【英文摘要】 A method of virtual crystal approximation calculation is suggested,which is basedon the all-electron scalar relativistic LMTO-ASA band structure method.The self-consistent iterarioncalculation approach in this method is emphasized,The application of this method to Al_xGa_(1-x)As alloyproduces reasonable virtual crystal band structures.国家和福建省自然科学基

Application of Cluster Expansion and Average-bond-energy Method to In_x.Ga_(1-x)As/GaAs System

【中文摘要】 把原子集团展开方法同平均键能方法相结合，建立了一种研究合金型应变层异质界面价带偏移的方法．应用此方法对ＩｎｘＧａ１－ｘＡｓ／ＧａＡｓ系统分别计算了以ＧａＡｓ和以ＩｎｘＧａ１－ｘＡｓ为衬底的两种不同的应变状态下的价带偏移（△Ｅｖ）随合金组份的变化规律．结果表明，由于应变的引入，该系统的面△Ｅｖ～Ｘ表现出大的非线性，且这一关系受到应变状态的显著影响．通过改变应变状态可使其为Ⅰ型或Ⅱ型超晶格以及金属．部分结果与有关的实验值和理论结果相符合． 【英文摘要】 A theoretical method for determining the valence-band offset (VBO) at strained alloy type heterojunctions is presented by combining the cluster expansion method and average-bond-energy method. Adopting this method; the VBO at InxGa1-xAs/GaAs system as a function of the alloy composition x is determined for two different strain conditions. It is shown that this variaton is in large nonlinearity due to the introduction of the elastic strain; and is exceedingly modulated by the strain condition. Present resul...国家自然科学基金,福建省自然科学基

THE AVERAGE BOND ENERGY AND THE VALENCE-BAND EDGE OFFSET AT THE INTERFACE OF STRAINED SUPERLATTICE InAs/InP

【中文摘要】 采用LMTO能带方法,对两种不同应变状态下(自由形变和以InP为衬底),应变层超晶格(InAs)_1(InP)_1(001)和与应变层超晶格的分子层相对应的应变体材料,以及无应变的体材料进行了第一原理计算,并采用冻结势方法求出了两种超晶格各分子层的平均键能。结果表明,能存在应变的情况下,异质界面两边的平均键能非常一致,且这种一致性受应变状态的影响很小,因而可以把它用来作为确定应变层超晶格价带边不连续值(△E_v)的普遍适用的参考能级。研究了应变对超晶格分子层能带结构的作用及其对△E_v值的影响。本文以平均键能为参考能级所得出的△M_v值与冻结势方法的结果及XPS的实验测量值非常一致。 【英文摘要】 The electronic structures of the strained superlattice (SLS) (InAs)1 (InP)1 (001)under two strain conditions (free-standing model and InP-substrate model) and the strained bulk materials corresponding to the molecular layers in the SLS as well as the unstrained bulk materials are calculated with the ab initio LMTO band structure method. The average bond energy of molecular layers in the two SLS are determined with the frozen-potential approach. The results show that the average bond energies are well aligne...国家自然科学基金;福建省自然科学基

AVERAGE-BOND-ENERGY MODEL: ITS PHYSICAL BASIS, ADVANTAGES, LIMITATIONS AND APPLICATIONS

【中文摘要】 平均键能模型是一种建立在数值基础上的用来确定半导体异质界面能带偏移的模型方法。本文首先对这一模型方法的物理基础进行了理论分析,并给予其完整的物理解释。通过与TB“pinned”模型、介电隙能级(DME)模型以及电中性点(CNP)模型的比较,揭示了各模型之间的相互关系,并分析了平均键能模型的优点及其局限性。在此基础上,本文应用这一模型方法对二十七种异质界面的价带偏移值进行了全面的计算,并对结果进行了广泛的分析和比较。结果表明:(1)阳离子浅d轨道是影响价带偏移理论值的一个重要因素;(2)界面偶极子势是决定异质界面价带偏移值的一个关键要素;(3)在与实验的比较上,平均键能模型的准确性优于几种其它的模型方法;(4)平均键能模型不适用于不具有sp~3杂化特性的材料系统。 【英文摘要】 In this paper, we present a full explanation for the average-bond-energy (ABE) model, which was developed, on the basis of numerical calculations, for the determination of valence-band offsets at heterointerfaces. By comparing it with the TB" pinned" model, the dielectric-midgap-energy model, and the charge-neutrality-point model, the relations between the four model theories are shown, and the advantages and limitationsof the ABE model are discussed. In this paper, the ABE model is applied to determining t..

应变层超晶格界面电荷转移效应和应变效应的能带计算

【中文摘要】 利用冻结势LMTO方法计算应变层超晶格(SLS)的电子结构,发现平均键能E_m主要由界面电荷转移效应决定,而E_m和价带顶能量E_m之差△E_n~m主要由应变效应决定,用应变材料的E_m为参考能级,可以由应变体材料的△E_n~m值直接给出SLS的价带能量偏移△E_n,所用到的不同应变状态下的△E_n~m(a∥)图可作为能带裁剪和设计特殊性能的SLS系统的重要参考标准。国家自然科学基金;福建省自然科学基

Ab initio Calculation of Valence-band Offsets for Lattice-matched Heterojunctions

【中文摘要】 In the light of our previous result that the average bond energy E_h valuelines up across heterojunction interfaces,in this paper,the valence-band offsets in ten hete-rojunctions have been calculated using the E_h as a reference level with the LMTO-ASAband-structure method.The calculated results are in excellent agreement with those fromthe more elaborate first-principles self-consistent interface calculations.As the presentmethod requires by far the smaller computational effort,it is very convenient fo... 【英文摘要】 In the light of our previous result that the average bond energy E_h value lines up across heterojunction interfaces,in this paper,the valence-band offsets in ten hete- rojunctions have been calculated using the E_h as a reference level with the LMTO-ASA band-structure method.The calculated results are in excellent agreement with those from the more elaborate first-principles self-consistent interface calculations.As the present method requires by far the smaller computational effort,it is very convenient f...Project supported by the National Natural Science Foundation of Chin

d State Effects in Theoretical Calculations of Band Offset in Heterostructures

【中文摘要】 由半导体的LMTO能带计算平均健能E_1,并以平均键能E_1作为参考能级计算共阴离子异质结的△E值.在LMTO能带计算中采用不同处理d态的计算方法,系统地研究d态在△E,理论计算中的作用,研究结果表明,d态对主要能带的杂化程度显著地影响△E值;适当处理d态之后,以E为参考能级的△E计算方法可以得到接近于界面自洽方法(SCIC或SCSC)的准确结果。 【英文摘要】 A first-principles approach for calculating the band offset △Ev in heterostructures with a common anion is presented. The ab iniio density functional LMTO calculation allows us to derive the average bond-antibands energy Eh which is considered as a reference level in our study. In this calculations,the d states are taken into account in some different schemes and the d state effects are revealed in band offset calculations. It is shown that the extent of d state hybridizing with the main band states plays a...厦门大学自然科学基