Surface analysis of epitaxially grown GeSn alloys with Sn contents between 15% and 18%
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in: Surface and interface analysis, Jahrgang 49.2017, Nr. 4, 01.04.2017, S. 297-302.
Publikationen: Beitrag in Fachzeitschrift › Artikel › Forschung › (peer-reviewed)
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TY - JOUR
T1 - Surface analysis of epitaxially grown GeSn alloys with Sn contents between 15% and 18%
AU - Kormoš, Lukas
AU - Kratzer, Markus
AU - Kostecki, Konrad
AU - Oehme, Michael
AU - Šikola, Tomas
AU - Kasper, Erich
AU - Schulze, Jörg
AU - Teichert, Christian
PY - 2017/4/1
Y1 - 2017/4/1
N2 - Metastable Germanium–tin (GeSn) layers with rather high Sn content between 15% and 18% grown on Si substrates by molecular beam epitaxy were analyzed for the morphological changes on a surface before and after reaching critical layer parameters (thickness, Sn content, and growth temperature) for surface roughening. Atomic-force microscopy investigations were performed as a function of thickness and separately for varying Sn concentrations in the GeSn layer. Epitaxial growth of metastable, uniform GeSn (15% Sn content) layers is obtained up to a critical thickness which increases from about 80 to above 200 nm by reducing the nominal growth temperature from 160 to 140 °C. Phase separation of the complete layer into tin-rich surface protrusions and a Ge-rich matrix takes place beyond the critical thickness. This surface roughening via phase separation was not observed in earlier investigations with lower Sn concentrations (<6%). Tin depletion in the GeSn matrix was confirmed by using energy-dispersive X-ray spectroscopy measurements showing residual Sn concentration below 5%. Additionally, creation of droplets with high concentration of tin on the surfaces was confirmed by energy-dispersive X-ray spectroscopy. Copyright © 2016 John Wiley & Sons, Ltd.
AB - Metastable Germanium–tin (GeSn) layers with rather high Sn content between 15% and 18% grown on Si substrates by molecular beam epitaxy were analyzed for the morphological changes on a surface before and after reaching critical layer parameters (thickness, Sn content, and growth temperature) for surface roughening. Atomic-force microscopy investigations were performed as a function of thickness and separately for varying Sn concentrations in the GeSn layer. Epitaxial growth of metastable, uniform GeSn (15% Sn content) layers is obtained up to a critical thickness which increases from about 80 to above 200 nm by reducing the nominal growth temperature from 160 to 140 °C. Phase separation of the complete layer into tin-rich surface protrusions and a Ge-rich matrix takes place beyond the critical thickness. This surface roughening via phase separation was not observed in earlier investigations with lower Sn concentrations (<6%). Tin depletion in the GeSn matrix was confirmed by using energy-dispersive X-ray spectroscopy measurements showing residual Sn concentration below 5%. Additionally, creation of droplets with high concentration of tin on the surfaces was confirmed by energy-dispersive X-ray spectroscopy. Copyright © 2016 John Wiley & Sons, Ltd.
KW - GeSn alloy
KW - phase separation
KW - epitaxy
U2 - 10.1002/sia.6134
DO - 10.1002/sia.6134
M3 - Article
VL - 49.2017
SP - 297
EP - 302
JO - Surface and interface analysis
JF - Surface and interface analysis
SN - 0142-2421
IS - 4
ER -