Ultrafast and low-power crystallization in Ge^sub 1^Sb^sub 2^Te^sub 4^ and Ge^sub 1^Sb^sub 4^Te^sub 7^ thin films using femtosecond laser pulses

Rapid and reversible switching between amorphous and crystalline phases of phase-change material promises to revolutionize the field of information processing with a wide range of applications including electronic, optoelectronics, and photonic memory devices. However, achieving faster crystallizati...

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Bibliographic Details
Published in:Applied optics (2004) 2018-01, Vol.57 (2), p.178
Main Authors: Sahu, Smriti, Sharma, Rituraj, Adarsh, K V, Manivannan, Anbarasu
Format: Article
Language:English
Subjects:
Amorphous materials
Antimony
Correlation analysis
Crystallization
Data processing
Excitation
Femtosecond pulses
Fluence
Inspection
Memory devices
Optoelectronics
Phase change materials
Phase transitions
Photonic crystals
Tellurium
Thin films
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Summary:Rapid and reversible switching between amorphous and crystalline phases of phase-change material promises to revolutionize the field of information processing with a wide range of applications including electronic, optoelectronics, and photonic memory devices. However, achieving faster crystallization is a key challenge. Here, we demonstrate femtosecond-driven transient inspection of ultrafast crystallization of as-deposited amorphous Ge1Sb2Te4 and Ge1Sb4Te7 thin films induced by a series of 120 fs laser pulses. The snapshots of phase transitions are correlated with the time-resolved measurements of change in the absorption of the samples. The crystallization is attributed to the reiterative excitation of an intermediate state with subcritical nuclei at a strikingly low fluence of 3.19  mJ/cm2 for Ge1Sb2Te4 and 1.59  mJ/cm2 for Ge1Sb4Te7. Furthermore, 100% volumetric crystallization of Ge1Sb4Te7 was achieved with the fluence of 4.78  mJ/cm2, and also reamorphization is seen for a continuous stimulation at the same repetition rate and fluence. A systematic confirmation of structural transformations of all samples is validated by Raman spectroscopic measurements on the spots produced by the various excitation fluences.
ISSN:1559-128X
2155-3165