Valence band structures of the phase change material Ge2 Sb2 Te5

Dohyun Lee; Sang Sun Lee; Wondong Kim; Chanyong Hwang; M. B. Hossain; Ngyuen Le Hung; Hyojin Kim; C. G. Kim; Hangil Lee; Han Na Hwang; Chan Cuk Hwang; Tae Yon Lee; Younseon Kang; Cheolkyu Kim; Dong Seok Suh; Kijoon H.P. Kim; Yoonho Khang

doi:10.1063/1.2825573

Valence band structures of the phase change material Ge2 Sb2 Te5

Dohyun Lee, Sang Sun Lee, Wondong Kim, Chanyong Hwang, M. B. Hossain, Ngyuen Le Hung, Hyojin Kim, C. G. Kim, Hangil Lee, Han Na Hwang, Chan Cuk Hwang, Tae Yon Lee, Younseon Kang, Cheolkyu Kim, Dong Seok Suh, Kijoon H.P. Kim, Yoonho Khang

Department of Physics and Chemistry

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

15 Scopus citations

Abstract

We report the experimental evidence of significant change of the valence band structure during crystallization of Ge2 Sb2 Te5 (GST). Amorphous GST, prepared by sputter deposition at room temperature (RT), transforms successively into face-centered-cubic (fcc) and a hexagonal-close-packed (hcp) structures at around 150 and 300 °C, respectively, during a stepwise temperature increase from RT to 350 °C. During temperature increase, ultraviolet photoemission spectra were in vacuo obtained using synchrotron radiation. The measurement of the amorphous and fcc GST shows that the difference between the maximum valence band edge and the Fermi level reduces by 0.35 eV during crystallization. For the fcc to hcp phase transformation, no band gap reduction was observed.

Original language	English
Article number	251901
Journal	Applied Physics Letters
Volume	91
Issue number	25
DOIs	https://doi.org/10.1063/1.2825573
State	Published - 2007

Bibliographical note

Funding Information:
Part of this work is supported by KORP through the “Development of Advanced Materials Metrology” project through Korea Research Institute of Standards and Science. Pohang Accelerator Laboratory is supported by Ministry of Science and Technology.

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@article{6a556949cb914496bf129a3e56ea2edd,

title = "Valence band structures of the phase change material Ge2 Sb2 Te5",

abstract = "We report the experimental evidence of significant change of the valence band structure during crystallization of Ge2 Sb2 Te5 (GST). Amorphous GST, prepared by sputter deposition at room temperature (RT), transforms successively into face-centered-cubic (fcc) and a hexagonal-close-packed (hcp) structures at around 150 and 300 °C, respectively, during a stepwise temperature increase from RT to 350 °C. During temperature increase, ultraviolet photoemission spectra were in vacuo obtained using synchrotron radiation. The measurement of the amorphous and fcc GST shows that the difference between the maximum valence band edge and the Fermi level reduces by 0.35 eV during crystallization. For the fcc to hcp phase transformation, no band gap reduction was observed.",

author = "Dohyun Lee and Lee, {Sang Sun} and Wondong Kim and Chanyong Hwang and Hossain, {M. B.} and Hung, {Ngyuen Le} and Hyojin Kim and Kim, {C. G.} and Hangil Lee and Hwang, {Han Na} and Hwang, {Chan Cuk} and Lee, {Tae Yon} and Younseon Kang and Cheolkyu Kim and Suh, {Dong Seok} and Kim, {Kijoon H.P.} and Yoonho Khang",

note = "Funding Information: Part of this work is supported by KORP through the “Development of Advanced Materials Metrology” project through Korea Research Institute of Standards and Science. Pohang Accelerator Laboratory is supported by Ministry of Science and Technology.",

year = "2007",

doi = "10.1063/1.2825573",

language = "English",

volume = "91",

journal = "Applied Physics Letters",

issn = "0003-6951",

publisher = "American Institute of Physics",

number = "25",

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TY - JOUR

T1 - Valence band structures of the phase change material Ge2 Sb2 Te5

AU - Lee, Dohyun

AU - Lee, Sang Sun

AU - Kim, Wondong

AU - Hwang, Chanyong

AU - Hossain, M. B.

AU - Hung, Ngyuen Le

AU - Kim, Hyojin

AU - Kim, C. G.

AU - Lee, Hangil

AU - Hwang, Han Na

AU - Hwang, Chan Cuk

AU - Lee, Tae Yon

AU - Kang, Younseon

AU - Kim, Cheolkyu

AU - Suh, Dong Seok

AU - Kim, Kijoon H.P.

AU - Khang, Yoonho

N1 - Funding Information: Part of this work is supported by KORP through the “Development of Advanced Materials Metrology” project through Korea Research Institute of Standards and Science. Pohang Accelerator Laboratory is supported by Ministry of Science and Technology.

PY - 2007

Y1 - 2007

N2 - We report the experimental evidence of significant change of the valence band structure during crystallization of Ge2 Sb2 Te5 (GST). Amorphous GST, prepared by sputter deposition at room temperature (RT), transforms successively into face-centered-cubic (fcc) and a hexagonal-close-packed (hcp) structures at around 150 and 300 °C, respectively, during a stepwise temperature increase from RT to 350 °C. During temperature increase, ultraviolet photoemission spectra were in vacuo obtained using synchrotron radiation. The measurement of the amorphous and fcc GST shows that the difference between the maximum valence band edge and the Fermi level reduces by 0.35 eV during crystallization. For the fcc to hcp phase transformation, no band gap reduction was observed.

AB - We report the experimental evidence of significant change of the valence band structure during crystallization of Ge2 Sb2 Te5 (GST). Amorphous GST, prepared by sputter deposition at room temperature (RT), transforms successively into face-centered-cubic (fcc) and a hexagonal-close-packed (hcp) structures at around 150 and 300 °C, respectively, during a stepwise temperature increase from RT to 350 °C. During temperature increase, ultraviolet photoemission spectra were in vacuo obtained using synchrotron radiation. The measurement of the amorphous and fcc GST shows that the difference between the maximum valence band edge and the Fermi level reduces by 0.35 eV during crystallization. For the fcc to hcp phase transformation, no band gap reduction was observed.

UR - http://www.scopus.com/inward/record.url?scp=37549001711&partnerID=8YFLogxK

U2 - 10.1063/1.2825573

DO - 10.1063/1.2825573

M3 - Article

AN - SCOPUS:37549001711

SN - 0003-6951

VL - 91

JO - Applied Physics Letters

JF - Applied Physics Letters

IS - 25

M1 - 251901

ER -

Valence band structures of the phase change material Ge2 Sb2 Te5

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