摘要:
基于Fermi黄金法则及Boltzmann方程碰撞项近似理论,推导建立了（001）弛豫Si（_1-x）Ge_x衬底外延四方晶系应变Si空穴散射几率与应力及能量的理论关系模型,包括离化杂质、声学声子、非极性光学声子及总散射概率（能量40 meV时）模型.结果表明：当Ge组分（x）低于0.2时,应变Si/（001）Si_（1-x）Ge_x材料空穴总散射概率随应力显著减小.之后,其随应力的变化趋于平缓.与立方晶系未应变Si材料相比,四方晶系应变Si材料空穴总散射概率最多可减小66%.应变Si材料空穴迁移率增强与其散射概率的减小密切相关,本文所得量化模型可为应变Si空穴迁移率及PMOS器件的研究与设计提供理论参考.
Abstract:
Based on Fermi＇s golden rule and the theory of Boltzmann collision term approximation, hole scattering mechanism in strained Si/（001）Sil-xGex, namely, tetragonal strained Si is studied, including ionized impurity, acoustic phonon, non-polar optical phonon and total scattering rates. It is found that the total scattering rate of hole in strained Si/（001）Si1-xGex decreases obviously with the increase of stress when Ge fraction （x） is less than 0.2 and the values continue to show a constant tendency. The total hole scattering rate of strained Si/（001）Si1-xGex decreases about 66% at most in comparison with one of unstrained Si. The hole mobility enhancement in strained Si material is due to the decrease of hole scattering rate. The result can provide valuable references for the research of hole mobility of strained Si materials and the design of PMOS devices.
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