Optical properties of β-FeSi2 under pressure

K. Takarabe; R. Teranishi; J. Oinuma; Y. Mori; T. Suemasu; S. Chichibu; F. Hasegawa

Optical properties of β-FeSi₂ under pressure

K. Takarabe, R. Teranishi, J. Oinuma, Y. Mori, T. Suemasu, S. Chichibu, F. Hasegawa

Research output: Contribution to journal › Article › peer-review

Abstract

We have investigated the high-pressure optical absorption of Iron disilicide, β-FeSi₂, thin films(90 nm in thickness) prepared from Si/Fe multilayers on Si (001) with template and SiO₂ capping. It is found that the experimental absorption coefficient in the range of photon energy of about 0.3 eV beyond the band gap is a few orders of magnitude larger than the first-principles calculated absorption coefficient. A possible explanation for this large absorption coefficient is the saddle-point exciton effect by the calculated band structure. No critical points with negative hydrostatic pressure coefficients such as those of Si and GaAs are observed in β-FeSi₂ near the band gap. The pressure coefficient for the direct band gap of β-FeSi₂ is determined to be 15.9 meV/GPa. This small coefficient is due to the negative deformation potential of the valence-band maximum, and the large bulk modulus of β-FeSi₂.

Original language	English
Article number	165215
Pages (from-to)	1652151-1652155
Number of pages	5
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	65
Issue number	16
Publication status	Published - 2002 Apr 15
Externally published	Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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title = "Optical properties of β-FeSi2 under pressure",

abstract = "We have investigated the high-pressure optical absorption of Iron disilicide, β-FeSi2, thin films(90 nm in thickness) prepared from Si/Fe multilayers on Si (001) with template and SiO2 capping. It is found that the experimental absorption coefficient in the range of photon energy of about 0.3 eV beyond the band gap is a few orders of magnitude larger than the first-principles calculated absorption coefficient. A possible explanation for this large absorption coefficient is the saddle-point exciton effect by the calculated band structure. No critical points with negative hydrostatic pressure coefficients such as those of Si and GaAs are observed in β-FeSi2 near the band gap. The pressure coefficient for the direct band gap of β-FeSi2 is determined to be 15.9 meV/GPa. This small coefficient is due to the negative deformation potential of the valence-band maximum, and the large bulk modulus of β-FeSi2.",

author = "K. Takarabe and R. Teranishi and J. Oinuma and Y. Mori and T. Suemasu and S. Chichibu and F. Hasegawa",

year = "2002",

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language = "English",

volume = "65",

pages = "1652151--1652155",

journal = "Physical Review B - Condensed Matter and Materials Physics",

issn = "0163-1829",

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number = "16",

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TY - JOUR

T1 - Optical properties of β-FeSi2 under pressure

AU - Takarabe, K.

AU - Teranishi, R.

AU - Oinuma, J.

AU - Mori, Y.

AU - Suemasu, T.

AU - Chichibu, S.

AU - Hasegawa, F.

PY - 2002/4/15

Y1 - 2002/4/15

N2 - We have investigated the high-pressure optical absorption of Iron disilicide, β-FeSi2, thin films(90 nm in thickness) prepared from Si/Fe multilayers on Si (001) with template and SiO2 capping. It is found that the experimental absorption coefficient in the range of photon energy of about 0.3 eV beyond the band gap is a few orders of magnitude larger than the first-principles calculated absorption coefficient. A possible explanation for this large absorption coefficient is the saddle-point exciton effect by the calculated band structure. No critical points with negative hydrostatic pressure coefficients such as those of Si and GaAs are observed in β-FeSi2 near the band gap. The pressure coefficient for the direct band gap of β-FeSi2 is determined to be 15.9 meV/GPa. This small coefficient is due to the negative deformation potential of the valence-band maximum, and the large bulk modulus of β-FeSi2.

AB - We have investigated the high-pressure optical absorption of Iron disilicide, β-FeSi2, thin films(90 nm in thickness) prepared from Si/Fe multilayers on Si (001) with template and SiO2 capping. It is found that the experimental absorption coefficient in the range of photon energy of about 0.3 eV beyond the band gap is a few orders of magnitude larger than the first-principles calculated absorption coefficient. A possible explanation for this large absorption coefficient is the saddle-point exciton effect by the calculated band structure. No critical points with negative hydrostatic pressure coefficients such as those of Si and GaAs are observed in β-FeSi2 near the band gap. The pressure coefficient for the direct band gap of β-FeSi2 is determined to be 15.9 meV/GPa. This small coefficient is due to the negative deformation potential of the valence-band maximum, and the large bulk modulus of β-FeSi2.

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