Germanium-silicon alloy and core-shell nanocrystals by gas phase synthesis

Mehringer C, Kloner C, Butz B, Winter B, Spiecker E, Peukert W (2015)


Publication Language: English

Publication Type: Journal article

Publication year: 2015

Journal

Publisher: Royal Society of Chemistry

Book Volume: 7

Pages Range: 5186--5196

Volume: 7

Issue: 12

Journal Issue: 12

DOI: 10.1039/c4nr06318j

Abstract

In this work we present a novel route to synthesize well defined germanium-silicon alloy (GexSi1-x) and core-shell nanocrystals (NCs) employing monosilane (SiH4) and monogermane (GeH4) as precursors in a continuously operated two-stage hot-wall aerosol reactor setup. The first hot-wall reactor stage (HWR I) is used to produce silicon (Si) seed particles from SiH4 pyrolysis in Argon (Ar). The resulting seeding aerosol is fed into the second reactor stage (HWR II) and a mixture of SiH4 and GeH4 is added. The ratio of the precursors in the feed, their partial pressures, the synthesis temperature in HWR II and the overall pressure are varied depending on the desired morphology and composition. Alloy particle production is achieved in the heterogeneous surface reaction regime, meaning that germanium (Ge) and Si are deposited on the seed surface simultaneously. The NCs can be synthesized with any desired composition, whilst maintaining a mean diameter around 30 nm with a geometric standard deviation (GSD) around 1.25. The absorption behavior and the related fundamental optical band gap energy in dependence on the alloy composition are exemplarily presented. They prove the possibility to tailor NC properties for electronical and opto-electronical applications. In the homogeneous gas phase reaction regime facetted Ge-Si core-shell structures are accessible. The Ge deposition on the seeds precedes the Si deposition due to different gas phase reaction kinetics of the precursors. The Si layer grows epitaxially on the Ge core and is around 5 nm thick.

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APA:

Mehringer, C., Kloner, C., Butz, B., Winter, B., Spiecker, E., & Peukert, W. (2015). Germanium-silicon alloy and core-shell nanocrystals by gas phase synthesis. Nanoscale, 7(12), 5186--5196. https://dx.doi.org/10.1039/c4nr06318j

MLA:

Mehringer, Christian, et al. "Germanium-silicon alloy and core-shell nanocrystals by gas phase synthesis." Nanoscale 7.12 (2015): 5186--5196.

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