Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 64: Focus Session: Semiconductor Heteroepitaxy on Nanopatterned Substrates

HL 64.6: Vortrag

Mittwoch, 9. März 2016, 17:45–18:00, H11

GaAs-based nanowire integration on silicon via template-assisted selective epitaxy — •Moritz Knoedler, Nicolas Bologna, Mattias Borg, Heinz Schmid, Giorgio Signorello, Davide Cutaia, Kirsten Moselund, Marta Rossell, and Heike Riel — IBM Research Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland

As the scaling-down of conventional Si microelectronics is approaching fundamental physical limits, novel materials are heavily being investigated as alternative channel materials, with III-V semiconductor compounds being particularly promising candidates. Thus far, III-V integration into Si technologies has been limited due to poor epitaxial material quality. Our group has recently demonstrated a novel method to directly integrate III-V nanostructures on silicon called template-assisted selective epitaxy (TASE). Nanowires are grown inside lithographically pre-defined oxide templates, allowing for precise tuning of composition and crystal quality, independent from their shape and substrate orientation.

Here we present a comprehensive investigation of GaAs-based epitaxy directly on Si wafers via TASE, by correlating growth parameters with crystal morphology. To this end, nanowires were grown with metal-organic chemical vapour deposition (MOCVD) under different conditions by varying template width, growth duration, temperature, group III molar flows and V/III precursor ratio. Crystal quality was then analyzed at atomic resolution by state-of-the-art double-aberration-corrected (scanning) transmission electron microscopy (STEM/TEM). Zinc blende/wurtzite polytypism and twin defect formation were investigated in detail.

Low-temperature and temperature-dependent micro photoluminescence (PL) spectroscopy was used to further characterize their optical properties. Significant photoemission of the nanostructures even at room temperature was observed. When the GaAs is surrounded by the oxide template or an AlGaAs shell luminescence is much enhanced, indicating reduced surface recombination velocity.