量子阱Si/SiGe/Si p型场效应管阈值电压和沟道空穴面密度模型  

Threshold-voltage and hole-sheet-density model of quantum well Si/SiGe/Si p field effect transistor

作　　者：李立[1] 刘红侠[1] 杨兆年[1] 

机构地区：[1]西安电子科技大学微电子学院宽禁带半导体材料与器件教育部重点实验室,西安710071

出　　处：《物理学报》2012年第16期348-354,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61076097;60936005)资助的课题~~

摘　　要：Si材料中较低的空穴迁移率限制了Si互补金属氧化物半导体器件在高频领域的应用.针对SiGe p型金属氧化物半导体场效应管(PMOSFET)结构,通过求解纵向一维泊松方程,得到了器件的纵向电势分布,并在此基础上建立了器件的阈值电压模型,讨论了Ge组分、缓冲层厚度、Si帽层厚度和衬底掺杂对阈值电压的影响.由于SiGe沟道层较薄,计算中考虑了该层价带势阱中的量子化效应.当栅电压绝对值过大时,由于能带弯曲和能级分裂造成SiGe沟道层中的空穴会越过势垒到达Si/SiO2界面,从而引起器件性能的退化.建立了量子阱SiGe PMOSFET沟道层的空穴面密度模型,提出了最大工作栅电压的概念,对由栅电压引起的沟道饱和进行了计算和分析.研究结果表明,器件的阈值电压和最大工作栅压与SiGe层Ge组分关系密切,Ge组分的适当提高可以使器件工作栅电压范围有效增大.The low hole mobility restricts the application of Si complementary metal-oxide-semiconductor in high frequency fields. In this paper, the SiGe p-metal-oxide-semiconductor field-effect-transistor （PMOSFET） is studied. By numeric modeling and analysis, the vertical potential distribution of the device is obtained through solving one-dimensional Poisson equations, and the threshold-voltage model is established. The effects of Ge-profile, thickness of Si buffer layer, thickness of Si cap layer and substrate doping on the threshold-voltage are discussed. In SiGe layer, the quantization effect of the potential well in valence band is taken into account. When the gate voltage is large enough, the holes in SiGe channel layer will transit to the Si/SiO2 interface due to band bending and energy level splitting, causing the degradation of device performance. Thus, the hole-sheet-density model in quantum channel of SiGe PMOSFET is established, and the concept of the maximum operating gate voltage is proposed, moreover the channel saturation induced by gate voltage is calculated and analyzed. The results show that the threshold voltage and the maximal operating gate voltage are related to Ge-profile, and a proper increase of Ge-profile can extend the range of the operating gate voltage effectively.

关 键 词：SIGE P型场效应管 阈值电压 量子阱 空穴面密度 

分 类 号：TN386[电子电信—物理电子学]