Removal mechanism and surface quality of crystal semiconductor materials in scratching tests with Berkovich indenter

摘要

Crystal semiconductor materials have been applied in a wide range of technology applications for their unique physical and mechanical properties. The groove depths of crystal semiconductor materials increased with the increasing scratching load while the effects of scratching speeds on the groove depths were not significant. Unlike the indentation process, the surfaces were sheared by the scratching load, leading to plastic flow and "ridge" at the edge of the scratches in the ranging of 10-40 mN. Cracks were observed at the edge of surface and extended to the free surface when the scratching load reached 60 mN, even resulting in the removal of materials due to brittle fracture. Meanwhile, the critical load of elastic-plastic deformation of single crystal Si and Ge was 2.24 mN and 2.26 mN, respectively. The original Si-I was converted to beta-Si and then to Si-XII (R8) and body-centered cubic (BC8), eventually returned to the Si-XII structure in the scratching process. Micro-chips and fracture debris indicated that brittle fracture and shear fracture occurred in the scratching experiments. In order to obtain relatively good surface quality of crystal semiconductor materials, the scratching load should be controlled below 40 mN and the scratching speed should be about 4 mu m/s.