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6CCVD Research

Electric, thermal, and optical properties of severely deformed Si processed by high-pressure torsion

At a Glance

Section titled ā€œAt a Glanceā€
MetadataDetails
Publication Date2022-12-01
JournalJournal of Applied Physics
AuthorsYoshifumi Ikoma, Kensuke Matsuda, Keigo Yoshida, Marina Takaira, Masamichi Kohno
InstitutionsKyushu University
Citations9

Abstract

Section titled ā€œAbstractā€

We report on electric, thermal, and optical properties of Si subjected to severe plastic deformation. Single-crystalline Si wafers were processed by high-pressure torsion (HPT) under a nominal pressure of 6 GPa. The HPT-processed samples consisted of metastable body-centered-cubic Si-III and rhombohedral Si-XII as well as diamond-cubic Si-I and amorphous phases. The metastable phases increased with increasing the number of anvil rotations (N). The resistivity of the single-crystalline Si (20 Ī© cm) increased to 50 Ī© cm after HPT processing for N = 10 and then it decreased to āˆ¼0.7 Ī© cm when increasing N to 100. Such an increase and a subsequent decrease in resistivity were attributed to the grain refinement and the increase in the volume fraction of semimetallic Si-III, respectively. The thermal conductivity was reduced by two orders of magnitude (āˆ¼3 W māˆ’1 Kāˆ’1) after HPT processing for N ā‰„ 50. A weak broad photoluminescence peak originating from Si-I nanograins appeared in the visible light region after annealing at 600 Ā°C. These results indicate that the resistivity, thermal conductivity, and photoluminescence of the HPT-processed Si strongly depend on the formation of metastable phases and grain refinement, which are induced by shear strain under high pressure.

Tech Support

Section titled ā€œTech Supportā€

Original Source

Section titled ā€œOriginal Sourceā€

References

Section titled ā€œReferencesā€
  1. 2000 - Bulk nanostructured materials from severe plastic deformation [Crossref]
  2. 2006 - Producing bulk ultrafine-grained materials by severe plastic deformation [Crossref]
  3. 2022 - Nanomaterials by severe plastic deformation: Review of historical developments and recent advances [Crossref]
  4. 2011 - Plastic deformation and allotropic phase transformations in zirconia ceramics during high-pressure torsion [Crossref]
  5. 2017 - High-pressure zinc oxide phase as visible-light-active photocatalyst with narrow band gap [Crossref]
  6. 2020 - Phase transformations, vacancy formation and variations of optical and photocatalytic properties in TiO2-ZnO composites by high-pressure torsion [Crossref]
  7. 2019 - The effect of severe plastic deformations on phase transitions and structure of solids [Crossref]
  8. 2019 - Severe plastic deformation of semiconductor materials using high-pressure torsion [Crossref]
  9. 2019 - Severe plastic deformation of polymers [Crossref]
  10. 2008 - Using high-pressure torsion for metal processing: Fundamentals and applications [Crossref]

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