Crystal and electronic structural changes during annealing in severely deformed Si containing metastable phases formed by high-pressure torsion

Yoshifumi Ikoma, Bumsoo Chon, Terumasa Yamasaki, Kazutoshi Takahashi, Katsuhiko Saito, Qixin Guo, Zenji Horita

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    6 Citations (Scopus)

    Abstract

    Single crystalline p- A nd n-type Si(100) wafers were severely deformed by high-pressure torsion (HPT) under a nominal pressure of 24 GPa. The HPT-processed samples consisted of metastable phases of body-centered-cubic Si-III and rhombohedral Si-XII, as well as diamond-cubic Si-I and amorphous phases. The photoemission spectroscopy using synchrotron radiation revealed that the valence band edge of the HPT-processed p- A nd n-type Si samples was located at ∼0.3 eV. Successive annealing in vacuum up to 200 °C led to the valence-band edge shift by ∼0.4 eV for both p- A nd n-type Si, and the disappearance of Si-III and Si-XII. These results indicated that the Si-III and Si-XII phases in the HPT-processed samples have smaller band gap than that of Si-I, and suggested that the valence-band edge shift after annealing is due to the mixture of Si-I and Si-IV phases in addition to the mid-gap pinning of the Fermi level.

    Original languageEnglish
    Article number101904
    JournalApplied Physics Letters
    Volume113
    Issue number10
    DOIs
    Publication statusPublished - Sep 3 2018

    All Science Journal Classification (ASJC) codes

    • Physics and Astronomy (miscellaneous)

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