Coherent optical phonons in different phases of Ge2Sb2Te5 upon strong laser excitation

被引：23

作者：

Hernandez-Rueda, J. ^{[1
]}

Savoia, A. ^{[2
]}

Gawelda, W. ^{[1
]}

Solis, J. ^{[1
]}

Mansart, B. ^{[3
]}

Boschetto, D. ^{[2
]}

Siegel, J. ^{[1
]}

机构：

[1] CSIC, Inst Opt, Laser Proc Grp, E-28006 Madrid, Spain

[2] Ecole Polytech, CNRS, Lab Opt Appl, ENSTA Paris Tech, F-91761 Palaiseau, France

[3] Univ Paris 11, Lab Phys Solides, CNRS, UMR 8502, F-91405 Orsay, France

来源：

APPLIED PHYSICS LETTERS | 2011年 / 98卷 / 25期

关键词：

amorphous semiconductors; antimony compounds; crystal structure; crystallisation; germanium compounds; high-speed optical techniques; laser beam effects; optical pumping; phase change materials; phonon spectra; photoconductivity; reflectivity; semiconductor thin films;

D O I：

10.1063/1.3601478

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

The transient reflectivity response of phase-change Ge2Sb2Te5 films to intense femtosecond laser pulses is studied by ultrafast coherent phonon spectroscopy. The three different phases (amorphous, fcc-, and hcp-crystalline), as well as laser-crystallized films, are investigated, featuring different photoexcited carrier and coherent optical phonon dynamics. At least two main phonon frequencies are identified for each phase/material and their evolution for increasing pump fluences is investigated for the fcc-crystalline phase and the laser-crystallized material, revealing strong differences. We find evidence that a considerable fraction of amorphous phase remains in the laser-crystallized material, which features a different phonon frequency, not related to other phases. These results are important for emerging strategies aimed at driving ultrafast phase transitions via coherent phonon excitation for applications in data storage. (C) 2011 American Institute of Physics. [doi:10.1063/1.3601478]

引用

页数：3

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