基于划刻实验的单晶锗材料去除机理研究

采用Cube压头对单晶锗进行变载与恒载纳米划刻实验, 利用扫描电子显微镜和原子力显微镜对已加工表面进行观测, 根据表面形貌将划刻过程分为延性域、脆塑转变域及脆性域三种, 对各个阶段的表面成型及材料去除方式进行了研究。使用最小二乘法对不同阶段划刻力进行非线性拟合, 并利用相关系数检验拟合函数可靠性, 结果表明划刻力与划刻深度存在强相关性。同时分析了单晶锗的弹性回复率随划刻距离的变化趋势, 结果表明工件的弹性回复率将从纯弹性阶段的1逐步回落至0.76左右。基于脆塑转变临界载荷, 以裂纹萌生位置作为脆塑转变标志, 首次结合工件已加工表面弹性回复, 提出一种适用于计算单晶锗的脆塑转变临界深度模型, 其脆塑转变临界深度为489 nm。

Material Removal Mechanism of Monocrystalline Germanium Based on Nano-scratch Experiment

A varied and constant load nano-scratch experiment on monocrystalline germanium was performed by Cube indenter. The surface morphology of the groove was observed by scanning electron microscope (SEM) and atomic force microscope (AFM) , and the scratch process was divided into three regimes, that is ductile regime, ductile-brittle transition regime and brittle regime based on observations. The material removal mechanism of different regimes was also analyzed. The least square method was used to establish nonlinear curve fittings between scratch depth and scratch force, and the correlation coefficient was used to verify reliability of fitting functions. Result shows that there is a strong correlation between scratch depth and scratch force. Meanwhile, the tendency of elastic recovery rate with scratch distance was analyzed. As the result shows, the elastic recovery rate gradually decreases from 1 in the pure elastic stage to about 0.76 in stable stage. Based on ductile-brittle translation critical load, a model is proposed to calculate the critical depth where the elastic recovery rate is firstly considered, and the ductile-brittle translation critical depth for monocrystalline germanium is 489 nm.