Si_(1-x)Ge_x/Si异质结构中热应力对临界厚度的影响

CALCULATION OF CRITICAL LAYER THICKNESS BY TAKING INTO ACCOUNT THE THERMAL STRAIN IN Si 1- x Ge x /Si STRAIN LAYER HETEROSTRUCTURES

系统分析了Ｓｉ１－ｘＧｅｘ／Ｓｉ外延生长中热应力对外延生长的影响．假设ＳｉＧｅ的线膨胀系数是随Ｇｅ的组分线性变化的，由此计算出热应变和应变能密度．根据能量平衡原理，当失配应变能密度加热应变能密度等于位错能密度时，外延层达到临界厚度，在Ｐｅｏｐｌｅ的基础上得出了改进的临界厚度计算公式．理论计算值与Ｐｅｏｐｌｅ的实验值更相近．

Effect of thermal strain on growth of SiGe strained layer on Si was analysed.Formulae for critical layer thickness were obtained by considering thermal strain in energy balance under the assumption of screw dislocation energy density equal to the sum of areal strain energy density and thermal strain energy density.The relationship between the thermal expansion coefficient associated with thermal strain and Ge content x was linear.The results are in good agreement with the experimental results reported.