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基于能量平衡条件,结合低温硅(LT-Si)剪切模量小于SiGe的实验结果,从螺位错形成模型出发,给出了基于LT-Si技术的赝晶SiGe应变弛豫机理.该机理指出,赝晶SiGe薄膜厚度小于位错形成临界厚度,可通过LT-Si缓冲层中形成位错释放应变;等于与大于临界厚度,位错在LT-Si层中优先形成,和文献报道中已观察到的实验结果相符合.同时,实验制备了基于LT-Si技术的弛豫Si0.8Ge0.2虚拟衬底材料.结果显示,位错被限制在LT-Si缓冲层中,弛豫度达到了85.09%,且在Si0.8Ge0.2中未观察到穿透位错,实验结果证实了赝晶Si0.8Ge0.2是通过在LT-Si缓冲层形成位错来释放应变的弛豫机理.
Based on the energy balance condition and the experimental results that the shear modulus of low temperature silicon (LT-Si) is smaller than that of SiGe, the relaxation mechanism of pseudomorphic SiGe strain based on LT-Si technique is given based on the screw dislocation formation model. It is pointed out that the thickness of pseudomorphic SiGe film is smaller than the critical thickness of dislocation formation and the strain can be released through the formation of dislocations in the LT-Si buffer layer. The dislocations equal to and greater than the critical thickness are preferentially formed in the LT-Si layer. The experimental results are consistent with the experimental results.At the same time, the LT-Si-based relaxed Si0.8 Ge0.2 virtual substrate material was prepared.The results show that the dislocations are confined in the LT-Si buffer layer, the relaxation reaches 85.09%, and no threading dislocations were observed in Si0.8Ge0.2. The experimental results confirmed that the pseudomorphic Si0.8Ge0.2 is a relaxation mechanism that releases strain by forming dislocations in the LT-Si buffer layer.