摘要:
单轴应变Si材料电子电导有效质量是理解其电子迁移率增强的关键因素之一,对其深入研究具有重要的理论意义和实用价值.本文从Schr¨odinger方程出发,将应力场考虑进来,建立了单轴应变Si材料导带E-k解析模型.并在此基础上,最终建立了单轴应变Si(001)任意晶向电子电导率有效质量与应力强度和应力类型的关系模型.本文的研究结果表明:1)单轴应力致电子迁移率增强的应力类型应选择张应力.2)单轴张应力情况下,仅从电子电导有效质量角度考虑,[110]/(001)晶向与[100]/(001)晶向均可.但考虑到态密度有效质量的因素,应选择[110]/(001)晶向.3)沿(001)晶面上[110]晶向施加单轴张应力时,若想进一步提高电子迁移率,应选取[100]晶向为器件沟道方向.以上结论可为应变Si nMOS器件性能增强的研究及导电沟道的应力与晶向设计提供重要理论依据.
Abstract:
Electronic conductivity effective mass is one of the key parameters studing electron mobility enhancement in unixial strained Si material. Its in-depth study has the significant theoretical and practical values. In this paper, we first establish the E-k relation for conduction band in a unixial strained Si material. And the model of electronic conductivity effective mass along an arbitrary directional channel in the uniaxial strained Si (001) is obtained. Our concluding results are described as follows. 1) Tensile stress should be used to enhance electron mobility for unixial trained Si. 2) In the case of tensile stress application, both [110]/(001) and [100]/(001) directions are the desirable ones from the evaluation of electronic conductivity effective mass. And [110]/(001) direction should be preferable when the density of state effective mass is taken into consideration. 3) If [100] direction becomes the channel direction under [110]/(001) uniaxial strain, the further electron mobility enhancement will occur. The results above can provide valuable reference for the conduction channel design related to stress and orientation in the strained Si nMOS device.
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