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

doi:10.15541/jim20180500

Abstract

Abstract:

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.

Key words: monocrystalline germanium, nano-scratch experiment, surface morphology, material removal, elastic recovery, ductile-brittle translation

CLC Number:

TN304

GENG Rui-Wen, YANG Xiao-Jing, XIE Qi-Ming, LI Rui, LUO Liang. Material Removal Mechanism of Monocrystalline Germanium Based on Nano-scratch Experiment[J]. Journal of Inorganic Materials, 2019, 34(8): 867-872.

Figures/Tables 11

Table 1 Nano-scratch test parameters

Test parameters	Value
Scratch crystal plane	(100)
Scratch distance/μm	500
Scratch speed/(μm?s^-1)	5
Load rate/(mN?μm^-1)	0.25
Normal load range/mN	0-125
Const normal load/mN	20/35/50

Fig. 1 Diagram of nano-scratch experiment

Fig. 2 Scratch morphology and its local amplification (a) Overall morphology; (b) Ductile regime; (c) DBT regime; (d) Brittle regime

Fig. 3 Curves of scratch distance vs depth for monocrystalline germanium

Fig. 4 AFM images of const load scratch (a) 20 mN; (b) 35 mN; (c) 50 mN

Fig. 5 Diagram of crack distribution for monocrystalline germanium

Table 2 Load and scratch distance ranges for diffirent regimes

Regime	Load range/mN	Scratch distancerange/μm
Ductile regime	0-48	100-298
DBT regime	48-100	298-500
Brittle regime	100-125	500-600

Fig. 6 Curves of scratch force vs distance

Fig. 7 Curves of scratch force vs depth for monocrystalline germanium (a) Normal force; (b) Tangental force

Fig. 8 Curve of elastic recovery rate during scratching

Fig. 9 Indenter-workpiece contract model in scratch process

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