单晶锗各向异性力学性能实验

Experiments on Anisotropic Mechanical Properties of Single Crystal Germanium

通过纳米压痕实验对单晶锗(100)、(110)、(111)晶面进行各向异性力学性能的分析研究。根据纳米压痕过程中获得的载荷-位移曲线并结合Oliver-Pharr理论对材料的弹性模量和硬度进行考察。实验结果表明:单晶锗在纳米压痕过程中发生明显的塑性变形,并且(110)晶面塑性最好,(100)晶面其次,(111)晶面塑性最差;硬度与弹性模量变化趋势相一致,在压入深度较小时,材料受表面效应的影响,硬度和弹性模量发生明显波动,而且由于单晶锗各个晶面上的原子密度以及晶面间距有较大的差异,单晶锗表现出稳定的各向异性,硬度和弹性模量大小依次为:(111)晶面、(110)晶面、(100)晶面。随着压入深度增加,硬度和弹性模量逐渐趋于稳定,大小依次为:(110)晶面、(100)晶面、(111)晶面。

The anisotropic mechanical properties of crystal surface of single crystal germanium, （100）, （110） and （111） were studied, through nano indentation experiments. According to the load displacement curves of nano indentation processes and the theory of Oliver-Pharr, the elastic modulus and the hardness of the materials were investigated. The experimental results show that obvious plastic deformation occurred in single crystal germanium in the process of nano indentation and the plasticity of Ge（110）is the best, Ge（100）is worse than Ge（111）, and the Ge（111）is the worst. And the hardness and the elastic modulus have similar change trend. When the indentation depth is shallow, significant fluctuations appeared on the hardness and the elastic modulus, affected by the surface effect. And because the atomic density of each crystal surface and the interplanar spacings are quite different, single-crystal germanium exhibits stable anisotropy, and the hardness and the elastic modulus rank from high to low as follows： （111） crystal plane, （110） crystal plane, （100） crystal plane. As the indentation depth increases, the hardness and the elastic modulus gradually stabilize, and the order from high to low are （110） crystal plane, （100） crystal plane, （111） crystal plane.