Phase transformations induced in relaxed amorphous silicon by indentation at room temperature
Date
2004-12-06
Authors
Haberl, Bianca
Bradby, J. E.
Swain, M. V.
Williams, J. S.
Munroe, P.
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American Institute of Physics
Abstract
The deformation behavior of self-ion-implanted amorphous-Si (a-Si) has been studied using spherical nanoindentation in both relaxed (annealed) and unrelaxed (as-implanted) a-Si. Interestingly, phase transformations were clearly observed in the relaxed state, with the load–unload curves from these samples displaying characteristic discontinuities and cross-sectional transmission electron microscopy images indicating the presence of high-pressure crystalline phases Si-III and Si-XII following pressure release. Thus, an amorphous to crystalline phase transformation has been induced by indentation at room temperature. In contrast, no evidence of a phase transformation was observed in unrelaxed a-Si, which appeared to deform via plastic flow of the amorphous phase. Furthermore, in situ electrical measurements clearly indicate the presence of a metallic Si phase during loading of relaxed a-Si but no such behavior was observed for unrelaxed a-Si.
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Keywords: Low-density amorphous phases; Nanoindentation; Room temperature; Unloading rates; Curve fitting; Deformation; High pressure effects; Indentation; Ion implantation; Phase transitions; Plastic flow; Amorphous silicon
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Applied Physics Letters
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