TY - JOUR
T1 - Crystal and electronic structural changes during annealing in severely deformed Si containing metastable phases formed by high-pressure torsion
AU - Ikoma, Yoshifumi
AU - Chon, Bumsoo
AU - Yamasaki, Terumasa
AU - Takahashi, Kazutoshi
AU - Saito, Katsuhiko
AU - Guo, Qixin
AU - Horita, Zenji
N1 - Funding Information:
This work was supported by a Grant-in-Aid for Scientific Research (S) (Grant No. JP26220909) from the Japan Society for the Promotion of Science. The authors acknowledge the facilities for HPT in the International Research Center on Giant Straining for Advanced Materials (IRC-GSAM) at Kyushu University. The photoemission experiments were performed at Saga University Beamline (SAGA-LS/BL13) with a proposal of H28-110V under the support of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
Publisher Copyright:
© 2018 Author(s).
PY - 2018/9/3
Y1 - 2018/9/3
N2 - 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.
AB - 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.
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U2 - 10.1063/1.5038160
DO - 10.1063/1.5038160
M3 - Article
AN - SCOPUS:85053001132
VL - 113
JO - Applied Physics Letters
JF - Applied Physics Letters
SN - 0003-6951
IS - 10
M1 - 101904
ER -