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Ex-situ n-type heavy doping of Ge1-xSnx epilayers by surface Sb deposition and pulsed laser melting
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Date
2022-07-10
Authors
Fontana, Daris
Sgarbossa, Francesco
Milazzo, Ruggero
Di Russo, Enrico
Galluccio, Emmanuele
De Salvador, Davide
Duffy, Ray
Napolitani, Enrico
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier B.V.
Published Version
Abstract
Ge1-xSnx alloys have attracted considerable attention for their promising electrical and optical properties. One of the main challenges for their successful implementation in devices concerns the fabrication of n-type heavily doped surface layers. In this work, a new methodology for ex-situ doping of Ge1-xSnx layers is investigated. It consists of the deposition of Sb atoms on the surface of Ge1-xSnx layers followed by pulsed laser melting (PLM) that ensures the diffusion of Sb into the alloy. We demonstrate that Sb is incorporated very efficiently within a relaxed Ge0.91Sn0.09 epilayer, with supersaturated 4 × 1020 cm−3 active concentrations, in line with literature records obtained in Ge1-xSnx with in-situ approaches. At the same time, we observe that the concentration of substitutional Sn close to the surface decreases from 9 to about 6 at. % after PLM, inducing a contraction of the lattice parameter perpendicular to the underlying Ge1-xSnx. These results demonstrate a possible route for ex-situ n-type heavy doping of Ge1-xSnx alloys, but indicate also that Sn redistribution and precipitation phenomena need to be carefully considered for a successful process development.
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Keywords
Antimony , Doping , Ge , GeSn , Laser processing , Pulsed laser melting
Citation
Fontana, D., Sgarbossa, F., Milazzo, R., Di Russo, E., Galluccio, E., De Salvador, D., Duffy, R. and Napolitani, E. (2022) 'Ex-situ n-type heavy doping of Ge1-xSnx epilayers by surface Sb deposition and pulsed laser melting', Applied Surface Science, 600, 154112 (7pp). doi: 10.1016/j.apsusc.2022.154112