Kinetics of Silver Photodiffusion Into Amorphous Ge20S80 Films: Case of Pre‐Reaction

Silver photodiffusion into amorphous chalcogenide has attracted much attention because of its potential applications for example in memory devices. For its development, it is important to know how Ag ions diffuse in chalcogenide layers upon light exposure. In this paper, the photo‐induced effect on...

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Bibliographic Details
Published in:Physica status solidi. A, Applications and materials science Applications and materials science, 2018-06, Vol.215 (12), p.n/a
Main Authors: Sakaguchi, Yoshifumi, Hanashima, Takayasu, Aoki, Hiroyuki, Asaoka, Hidehito, Ahmed Simon, Al‐Amin, Mitkova, Maria
Format: Article
Language:English
Subjects:
amorphous chalcogenide
Chalcogenides
Exposure
Fragments
Memory devices
neutron reflectivity
Reaction kinetics
Reaction time
Reflectance
Silicon substrates
Silver
silver photodiffusion
X-ray diffraction
X‐ray reflectivity
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Summary:Silver photodiffusion into amorphous chalcogenide has attracted much attention because of its potential applications for example in memory devices. For its development, it is important to know how Ag ions diffuse in chalcogenide layers upon light exposure. In this paper, the photo‐induced effect on “pre‐reacted” films before light exposure, originating from Ag/Ge20S80/Si substrate and Ge20S80/Ag/Si substrate is investigated, using neutron reflectivity, X‐ray reflectivity, and X‐ray diffraction. Two types of “pre‐reacted” films according to the original stacking order are obtained. In both cases, a pure Ag layer almost disappeared, and there is a small amount of monoclinic Ag2S. The reaction time for the photodiffusion is shorter, in both cases, than that in Ag/Ge20S80 with a pure Ag layer, indicating a different reaction process. After prolonged light exposure, a uniform amorphous reaction layer is produced in the films originating from the Ag/Ge20S80/Si substrate, while both an amorphous reaction product and the Ag2S fragments exist in the films originating from Ge20S80/Ag/Si substrate. The mechanism of the specific photo‐reaction is discussed in terms of the role of the Ag2S fragments. The effect of “pre‐reaction” before light exposure on silver photodiffusion into Ag/amorphous Ge20S80 films is investigated by neutron reflectivity, X‐ray reflectivity, and X‐ray diffraction measurements. There are two types of the pre‐reacted films according to the stacking order. Both types of the films have the catalytic fast photo‐reaction rate.
ISSN:1862-6300
1862-6319
DOI:10.1002/pssa.201800049