【作者】 宋建军；

【导师】 张鹤鸣；

【作者基本信息】 西安电子科技大学 ， 微电子学与固体电子学， 2008， 博士

【摘要】 Si基(Si、SiGe)应变材料迁移率高、能带结构可调,且其应用与Si工艺兼容,是当前国内外关注的研究领域和研究发展重点,在高速／高性能器件和电路中有极大的应用前景。能带结构是深入研究Si基应变材料基本属性,发展高速／高性能器件和电路的重要理论基础。目前,有关Si基应变(张应变、压应变)材料能带结构的理论研究鲜有报道,基于Si基应变材料物理机制,系统研究其能带结构有重要理论意义和应用价值。本论文基于Si基应变材料对称性分析,研究确定了双轴应变导带能谷的分裂及其简并度,通过线性形变势理论分析获得了导带能谷的能级。基于薛定格方程,考虑应变产生的形变势场,采用K·P微扰理论,研究建立了Si基应变材料导带E(k)-k关系模型,获得了导带能量分布、导带底k矢位置及其电子有效质量。同时,在研究应变哈密顿微扰基础上,建立了Si基双轴应变材料价带E(k)-k关系模型,获得了带边、亚带边、旋轨分裂带Γ点处能级、任意k矢方向的能量分布及空穴有效质量。通过以上研究,建立了Si基双轴应变材料的能带结构模型,该模型适用于任意晶向应变材料,为Si基应变材料及器件性能增强的研究设计奠定了重要理论基础。基于能带结构模型,研究建立了Si基双轴应变材料导带底和价带顶的态密度有效质量、状态密度、有效状态密度及本征载流子浓度模型,为Si基应变材料及器件电学特性研究奠定了重要的物理基础。研究建立了适用于CASTEP的应变Si物理参数模型,探讨了利用CASTEP软件分析应变Si能带结构的方法,为Si基应变材料能带结构及相关物理参数的研究分析提供了辅助手段。基于广义Hook定律,研究了Ge组份与应力间的转化关系,据此可将本文所建立的Si基应变材料能带结构等各种模型转化为直接利用应力强度表征的模型,实现了直接用应力强度研究、设计Si基双轴应变材料与器件,扩展了本文研究成果的应用范围。更多还原

【Abstract】 There has been a lot of interest in the Si-based (Si、SiGe) strained materials lately with its advantage of high-mobility, adjustable band structure and compatible technology with traditional silicon processing and wide application in the high-speed and high-performance devices and circuits. The band structure is the theoretical basis of the research on the base attribute and the design of the high-speed and high-performance devices and circuits. However, Up to now there have been few reported results for the band structure of the Si-based strained materials. Based on the basic physical mechanism of the Si-based strained materials, system study on the band structure has essential theoretical significance and practical value.Based on an analysis of symmetry under strain, the number of equivalent CB edge energy extrema is presented. Using K·P method with the help of perturbation theory, E(k)-k relation near minima CB energy followed from linear deformation potential theory is determined, from which the parameters extracted, namely, the position of the extremal point, the electronic effective masses are obtained. With the frame of K·P theory, the E(k)-k relation has been derived by taking strained Hamiltonian perturbation into account. The corresponding model were obtained such as the energy level of first valence band, second valence band and spin-orbit splitting band at theΓposition and the hole effective mass along arbitrarily k wavevector direction. The band structure model is applicable for the Si-based strained materials on arbitrarily oriented substrate and essensail to the investigation into the performance enhancement of the Si-based strained materials and devices.Using the parameters of band structure, the models of density-of-states effective mass, density-of-states and intrinsic carrier concentration of the conduction band and valence band were obtained. The models are the key parameters of the investigation into the electricity property of the Si-based strained materials and devices.The physical structure models of strained Si used for CASTEP calculation were specified. How to calculate the band structures of strained Si by CASTEP approach was discussed. As an assistant means, the CASTEP approach can be used for the investigation into the band structure and other basic physical properties of the Si-based strained materials.Based on Hook law, the transformation model between Ge fraction and stress was established, which makes the band structure and other basic physical properties of the Si-based strained materials characterized by stress and broadens the scope of the application of the research results.更多还原