Cross-sectional phase analysis of single crystalline silicon indented by Rockwell indenter
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Cross-sectional phase analysis of single crystalline silicon indented by Rockwell indenter G
Sung-Soon Kim, Han-Seog Oh, Seong-Min Jeong, Hong-Lim Lee. Department of Ceramic Engineering, Yonsei University 134 Shinchon-Dong, Seodaemoon-Gu, Seoul, 120-749, Korea G
ABSTRACT G
This study of the indentation behavior of Si has revealed a complex process of mechanical deformation. As loading time increased, Si-XII and Si-III disappeared and only a-Si appeared in (111) samples. As loading time increased, crack was generated and residual stress was removed. At fast loading rate, the deformation behavior appears predominantly elastic. On the contrary, at slow loading rate, catastrophic plastic deformation occurred during loading stage. We have observed crack behavior which occurred under spherical indentation in crystalline silicon. Method which was used in our research for cross-sectional observation exaggerated generation and propagation of cracks. Our method prepares to observe crack behavior. But it is not profit to observe to phase transformation G
INTRODUCTION The response of crystalline silicon to indentation has been a topic of interest for many years, and it is now well established that this material undergoes a series of high-pressure phase changes when subjected to high pressures. Most results of investigation used to directly confirm the phase transformation by indentation are plane view. The information from plane view observation is limited on studying the actual affected region of indentation on the material from surface to inside. In order to get a better understanding of the phenomenon occurring during indentation, the cross-sectional study is required. Lack of this kind of information is mainly because of the difficulty in preparing a suitable cross-section sample for observing by TEM or other instruments [1]. In this work, cross-sectional observation was performed to observe crack propagation and phase transformation. And phase transformations on both loading time and loading rate were also studied. Micro-Raman spectroscopy was used to observe the phase transition of the single crystalline silicon.
P8.6.1
EXPERIMENTAL DETAILS A series of indentation were made on (111)/(100) single crystalline with Rockwell c-type tip
(radius 200µm) at 50N. All indentations were made with an Universal Test Machine at ambient pressure and room temperature. Four loading times (5, 10, 20, 30sec) were used for loading time experiments. Two loading rate(0.1, 5mm/min) were used for loading rate experiments. MicroRaman spectroscopy was used for the analysis of the indentation-induced transformations. Samples were prepared for cross-sectional observation by conducting two wafers. Crystal wax was used to bonding the interface of wafers. Then samples were polished for mirror surface. Indentations were performed at bonded interface of two wafers. Optical microscope was used to observe cross-section.G G
DISCUSSION Effect of loading time
Phase transformations loading time were studied. 5, 10, 20, 30 s were chosen. Raman shifts
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