纳米压痕条件下单晶锗的尺寸效应

采用准静态法对单晶锗(111)晶面进行了纳米压痕实验,对单晶锗(111)晶面的位移-载荷曲线及硬度-压深曲线进行了分析。结果表明,在压入深度为471.36nm时,单晶锗(111)晶面的加载曲线上出现突进点,随着压入深度的进一步增加,突进点逐渐增多。该点对应为单晶锗(111)晶面由塑性变形向脆性断裂转变的临界点。单晶锗卸载曲线上出现突退点,突退点对应为单晶锗由弹性变形向塑性变形转变的临界点。单晶锗(111)晶面的硬度和弹性模量均呈现出随压入深度的增加而减小的趋势,表现出明显的尺寸效应。基于Nix-Gao模型对单晶锗(111)晶面的硬度与压深关系进行曲线拟合,得到无尺寸效应时的纳米硬度为8.399GPa,微观特征长度为131.907nm,尺寸效应因子为0.168。

Size Effect of Single Crystal Germanium under Nanoindentation Conditions

The nano-indentation experiment was carried out on crystal plane of single crystal Ge(111) by quasi-static method. The displacement-load curve and hardness-depth curve of Ge(111) were analyzed. The results show that when the indentation depth is 471.36 nm,a spurt point appears on the loading curve of the single crystal Ge (111) crystal plane. As the indentation depth increases further,the spurt point increases gradually. This point corresponds to the critical point at which the single crystal Ge (111) crystal plane changes from plastic deformation to brittle fracture. The retreat point appears on the unloading curve of Ge(111),and the retreat point corresponds to the critical point where the Ge (111) turns from elastic deformation to plastic deformation. The hardness and elastic modulus of Ge (111) are decreasing with the increase of the indentation depth,showing a significant size effect. The relationship between the hardness and depth of Ge(111) is obtained based on Nix-Gao model. The nanohardness without size effect is 8.399 GPa,the microscopic feature length is 131.907 nm,and the size effect factor is 0.168.