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Electrical properties of amorphous chalcogenide/silicon heterojunctions modified by ion implantation

Electrical properties of amorphous chalcogenide/silicon heterojunctions modified by ion implantation
Electrical properties of amorphous chalcogenide/silicon heterojunctions modified by ion implantation
Doping of amorphous chalcogenide films of rather dissimilar bonding type and resistivity, namely, Ga-La-S, GeTe, and Ge-Sb-Te by means of ion implantation of bismuth is considered. To characterize defects induced by ion-beam implantation space-charge-limited conduction and capacitance-voltage characteristics of amorphous chalcogenide/silicon heterojunctions are investigated. It is shown that ion implantation introduces substantial defect densities in the films and their interfaces with silicon. This comes along with a gradual decrease in the resistivity and the thermopower coefficient. It is shown that conductivity in GeTe and Ge-Sb-Te films is consistent with two-type carrier conduction model. It is anticipated that ion implantation renders electrons to become less localized than holes leading to electron conductivity in certain cases as, for example, in GeTe. The modification of electronic properties which stems from the ion-solid interaction processes results in the modification of the composition of the films as identified by elemental analyses with the help of Rutherford Backscattering Spectrometry. At the same time, much higher interface trap densities are observed in the implanted chalcogenide/silicon interfaces. In terms of interface trap built-up, ion implantation influences Ge-Sb-Te and Ga-La-S interfaces with silicon distinctly different. Much higher density of acceptor-like interface trap is observed in Ga-La-S/Si interfaces suggesting the ion-beam induced interface traps are not solely due to silicon dangling bond defect.
Federenko, Y.
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Hughes, M.A.
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Colaux, J.
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Jeynes, C.
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Gwilliam, R.M.
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Homewood, K.
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Yao, J.
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Hewak, D.W.
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Lee, T.H.
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Elliott, S.R.
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Gholipour, B.
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Curry, R.J.
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Federenko, Y.
e585ae8a-225a-4866-9ea1-a2c5d08330d5
Hughes, M.A.
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Colaux, J.
d4bc32ff-b5a2-42dc-9b2a-3b193c3ce5db
Jeynes, C.
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Gwilliam, R.M.
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Homewood, K.
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Yao, J.
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Hewak, D.W.
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Lee, T.H.
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Elliott, S.R.
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Gholipour, B.
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Curry, R.J.
1ae2a4da-7efe-4333-a34e-0ec20ae95154

Federenko, Y., Hughes, M.A., Colaux, J., Jeynes, C., Gwilliam, R.M., Homewood, K., Yao, J., Hewak, D.W., Lee, T.H., Elliott, S.R., Gholipour, B. and Curry, R.J. (2014) Electrical properties of amorphous chalcogenide/silicon heterojunctions modified by ion implantation. SPIE Photonics West 2014, San Francisco, United States. 01 - 06 Feb 2014. 8 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

Doping of amorphous chalcogenide films of rather dissimilar bonding type and resistivity, namely, Ga-La-S, GeTe, and Ge-Sb-Te by means of ion implantation of bismuth is considered. To characterize defects induced by ion-beam implantation space-charge-limited conduction and capacitance-voltage characteristics of amorphous chalcogenide/silicon heterojunctions are investigated. It is shown that ion implantation introduces substantial defect densities in the films and their interfaces with silicon. This comes along with a gradual decrease in the resistivity and the thermopower coefficient. It is shown that conductivity in GeTe and Ge-Sb-Te films is consistent with two-type carrier conduction model. It is anticipated that ion implantation renders electrons to become less localized than holes leading to electron conductivity in certain cases as, for example, in GeTe. The modification of electronic properties which stems from the ion-solid interaction processes results in the modification of the composition of the films as identified by elemental analyses with the help of Rutherford Backscattering Spectrometry. At the same time, much higher interface trap densities are observed in the implanted chalcogenide/silicon interfaces. In terms of interface trap built-up, ion implantation influences Ge-Sb-Te and Ga-La-S interfaces with silicon distinctly different. Much higher density of acceptor-like interface trap is observed in Ga-La-S/Si interfaces suggesting the ion-beam induced interface traps are not solely due to silicon dangling bond defect.

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Published date: February 2014
Venue - Dates: SPIE Photonics West 2014, San Francisco, United States, 2014-02-01 - 2014-02-06
Organisations: Optoelectronics Research Centre, Electrochemistry

Identifiers

Local EPrints ID: 363255
URI: http://eprints.soton.ac.uk/id/eprint/363255
PURE UUID: 126a0c5b-618a-47db-bd75-1df10b6cdce8
ORCID for D.W. Hewak: ORCID iD orcid.org/0000-0002-2093-5773

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Date deposited: 21 Mar 2014 12:11
Last modified: 20 Jul 2019 01:21

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