Femtosecond-laser-induced modifications of Ge2Sb2Te5 thin films: Permanent optical change without amorphization

Søren Møller; Emil H.  Eriksen; Peter Tønning; Pia Bomholt Jensen; Jacques Chevallier; Peter Balling

doi:10.1016/j.apsusc.2019.01.070

Femtosecond-laser-induced modifications of Ge₂Sb₂Te₅ thin films: Permanent optical change without amorphization

Søren Møller, Emil H. Eriksen , Peter Tønning, Pia Bomholt Jensen, Jacques Chevallier, Peter Balling

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

6 Citations (Scopus)

Abstract

Modifications induced by ultrashort laser pulses have been investigated in crystalline Ge ₂ Sb ₂ Te ₅ thin films. The observations comprise optical and structural changes, amorphization, and ablation. By combining optical microscopy and cross-sectional scanning- and transmission electron microscopy, it is found that the threshold for permanent change of the optical properties of Ge ₂ Sb ₂ Te ₅ – responsible for the reduced optical reflectivity – is slightly lower than that for amorphization; no further change in reflectivity is seen upon amorphization. The laser-fluence thresholds for amorphization and change of the optical properties both show a strong dependence on film thickness that can be explained thermally by two-temperature simulations. In the case of sufficiently thick films, two distinct low- and high-fluence ablation thresholds are found. The mechanisms of the ablation thresholds are discussed, and it is concluded that ablation in the low-fluence regime proceeds by photomechanical spallation.

Original language	English
Journal	Applied Surface Science
Volume	476
Issue	May
Pages (from-to)	221-231
Number of pages	11
ISSN	0169-4332
DOIs	https://doi.org/10.1016/j.apsusc.2019.01.070
Publication status	Published - 2019

Keywords

ABLATION
Ablation
Amorphization
CRYSTALLIZATION
Ge2Sb2Te5
IMPACT
METAL TARGETS
PHASE-TRANSITIONS
Phase-change materials
SPALLATION
SURFACE
TRANSFORMATIONS
Thin films

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10.1016/j.apsusc.2019.01.070

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@article{5f5ebf9db8ca4088a70d54ba2e1f443f,

title = "Femtosecond-laser-induced modifications of Ge2Sb2Te5 thin films: Permanent optical change without amorphization",

abstract = "Modifications induced by ultrashort laser pulses have been investigated in crystalline Ge 2 Sb 2 Te 5 thin films. The observations comprise optical and structural changes, amorphization, and ablation. By combining optical microscopy and cross-sectional scanning- and transmission electron microscopy, it is found that the threshold for permanent change of the optical properties of Ge 2 Sb 2 Te 5 – responsible for the reduced optical reflectivity – is slightly lower than that for amorphization; no further change in reflectivity is seen upon amorphization. The laser-fluence thresholds for amorphization and change of the optical properties both show a strong dependence on film thickness that can be explained thermally by two-temperature simulations. In the case of sufficiently thick films, two distinct low- and high-fluence ablation thresholds are found. The mechanisms of the ablation thresholds are discussed, and it is concluded that ablation in the low-fluence regime proceeds by photomechanical spallation. ",

keywords = "ABLATION, Ablation, Amorphization, CRYSTALLIZATION, Ge2Sb2Te5, IMPACT, METAL TARGETS, PHASE-TRANSITIONS, Phase-change materials, SPALLATION, SURFACE, TRANSFORMATIONS, Thin films",

author = "S{\o}ren M{\o}ller and Eriksen, {Emil H.} and Peter T{\o}nning and Jensen, {Pia Bomholt} and Jacques Chevallier and Peter Balling",

year = "2019",

doi = "10.1016/j.apsusc.2019.01.070",

language = "English",

volume = "476",

pages = "221--231",

journal = "Applied Surface Science",

issn = "0169-4332",

publisher = "Elsevier B.V.",

number = "May",

}

Femtosecond-laser-induced modifications of Ge₂Sb₂Te₅ thin films: Permanent optical change without amorphization. / Møller, Søren; Eriksen , Emil H. ; Tønning, Peter et al.
In: Applied Surface Science, Vol. 476, No. May, 2019, p. 221-231.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Femtosecond-laser-induced modifications of Ge2Sb2Te5 thin films

T2 - Permanent optical change without amorphization

AU - Møller, Søren

AU - Eriksen , Emil H.

AU - Tønning, Peter

AU - Jensen, Pia Bomholt

AU - Chevallier, Jacques

AU - Balling, Peter

PY - 2019

Y1 - 2019

N2 - Modifications induced by ultrashort laser pulses have been investigated in crystalline Ge 2 Sb 2 Te 5 thin films. The observations comprise optical and structural changes, amorphization, and ablation. By combining optical microscopy and cross-sectional scanning- and transmission electron microscopy, it is found that the threshold for permanent change of the optical properties of Ge 2 Sb 2 Te 5 – responsible for the reduced optical reflectivity – is slightly lower than that for amorphization; no further change in reflectivity is seen upon amorphization. The laser-fluence thresholds for amorphization and change of the optical properties both show a strong dependence on film thickness that can be explained thermally by two-temperature simulations. In the case of sufficiently thick films, two distinct low- and high-fluence ablation thresholds are found. The mechanisms of the ablation thresholds are discussed, and it is concluded that ablation in the low-fluence regime proceeds by photomechanical spallation.

AB - Modifications induced by ultrashort laser pulses have been investigated in crystalline Ge 2 Sb 2 Te 5 thin films. The observations comprise optical and structural changes, amorphization, and ablation. By combining optical microscopy and cross-sectional scanning- and transmission electron microscopy, it is found that the threshold for permanent change of the optical properties of Ge 2 Sb 2 Te 5 – responsible for the reduced optical reflectivity – is slightly lower than that for amorphization; no further change in reflectivity is seen upon amorphization. The laser-fluence thresholds for amorphization and change of the optical properties both show a strong dependence on film thickness that can be explained thermally by two-temperature simulations. In the case of sufficiently thick films, two distinct low- and high-fluence ablation thresholds are found. The mechanisms of the ablation thresholds are discussed, and it is concluded that ablation in the low-fluence regime proceeds by photomechanical spallation.

KW - ABLATION

KW - Ablation

KW - Amorphization

KW - CRYSTALLIZATION

KW - Ge2Sb2Te5

KW - IMPACT

KW - METAL TARGETS

KW - PHASE-TRANSITIONS

KW - Phase-change materials

KW - SPALLATION

KW - SURFACE

KW - TRANSFORMATIONS

KW - Thin films

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DO - 10.1016/j.apsusc.2019.01.070

M3 - Journal article

SN - 0169-4332

VL - 476

SP - 221

EP - 231

JO - Applied Surface Science

JF - Applied Surface Science

IS - May

ER -

Femtosecond-laser-induced modifications of Ge₂Sb₂Te₅ thin films: Permanent optical change without amorphization

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Keywords

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