TY - JOUR
T1 - Fabrication of nanograined silicon by high-pressure torsion
AU - Ikoma, Yoshifumi
AU - Hayano, Kazunori
AU - Edalati, Kaveh
AU - Saito, Katsuhiko
AU - Guo, Qixin
AU - Horita, Zenji
AU - Aoki, Toshihiro
AU - Smith, David J.
N1 - Funding Information:
Acknowledgements This work was supported in part by a Grant-in-Aid for Scientific Research from the MEXT Japan, in Innovative Areas ‘‘Bulk Nanostructured Metals’’ (Nos. 22102004, 25102708). The authors also acknowledge use of facilities in the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University.
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2014/10
Y1 - 2014/10
N2 - This paper describes fabrication of Si nanograins through allotropic phase transformation by concurrent application of high pressure and intense straining using high-pressure torsion (HPT). Single-crystalline Si(100) wafers were processed by HPT under a pressure of 24 GPa at room temperature. X-ray diffraction and Raman analysis revealed that the HPT-processed samples were composed of metastable Si-III and Si-XII phases and amorphous phases in addition to the original diamond-cubic Si-I phase. It was found that nanograins formed because the Si-I diamond phase had transformed to high-pressure phases (Si-II, Si-XI, and Si-V) having metallic nature, and it then became easier to generate a high density of dislocations to form grain boundaries. The high-pressure phases were further transformed to the Si-XII and Si-III phases via the Si-II phase upon unloading and they existed as metastable phases at ambient pressure. Subsequent annealing at 873 K gave rise to reverse transformation to Si-I but with nanograin sizes. Although no appreciable photoluminescence (PL) peak was observed from the HPT-processed sample, a broad PL peak centered around 600 nm was detected from the annealed sample due to quantum confinement in the Si-I nanograins.
AB - This paper describes fabrication of Si nanograins through allotropic phase transformation by concurrent application of high pressure and intense straining using high-pressure torsion (HPT). Single-crystalline Si(100) wafers were processed by HPT under a pressure of 24 GPa at room temperature. X-ray diffraction and Raman analysis revealed that the HPT-processed samples were composed of metastable Si-III and Si-XII phases and amorphous phases in addition to the original diamond-cubic Si-I phase. It was found that nanograins formed because the Si-I diamond phase had transformed to high-pressure phases (Si-II, Si-XI, and Si-V) having metallic nature, and it then became easier to generate a high density of dislocations to form grain boundaries. The high-pressure phases were further transformed to the Si-XII and Si-III phases via the Si-II phase upon unloading and they existed as metastable phases at ambient pressure. Subsequent annealing at 873 K gave rise to reverse transformation to Si-I but with nanograin sizes. Although no appreciable photoluminescence (PL) peak was observed from the HPT-processed sample, a broad PL peak centered around 600 nm was detected from the annealed sample due to quantum confinement in the Si-I nanograins.
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U2 - 10.1007/s10853-014-8250-z
DO - 10.1007/s10853-014-8250-z
M3 - Article
AN - SCOPUS:84904726848
VL - 49
SP - 6565
EP - 6569
JO - Journal of Materials Science
JF - Journal of Materials Science
SN - 0022-2461
IS - 19
ER -