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MA: Fachverband Magnetismus

MA 8: SKM Dissertation-Prize 2017

MA 8.4: Hauptvortrag

Montag, 20. März 2017, 11:45–12:10, HSZ 04

Group IV Epitaxy for Advanced Nano- and Optoelectronic Applications — •Stephan Wirths — Peter Grünberg Institut (PGI 9), Forschungszentrum Jülich, 52425 Jülich, Germany — IBM Research - Zurich, 8803 Rüschlikon, Switzerland

The monolithic, large-scale integration of photonics on Si is limited by the inability of Si to emit light efficiently. In this context, Sn-based group IV semiconductors attracted increasing scientific interest during the last decades due to the possibility to pass the indirect-to-direct bandgap transition by alloying Ge with Sn. However, the quality of epitaxially grown GeSn and SiGeSn layers on Si substrates is limited by the low solid solubility of Sn in (Si)Ge (< 1 at.%) and the large lattice mismatch (> 15 %). Here, a low-temperature reduced pressure chemical vapor deposition process was developed for the growth of (Si)GeSn epilayers directly on Si(001) and on Ge-buffered Si(001). High growth rates (> 50 nm/min) at low growth temperatures < 400^∘C are key for Si-Ge-Sn alloys with exceptionally high monocrystalline quality and Sn concentrations far beyond the solid solubility of Sn in (Si)Ge. It was shown that the plastic strain relaxation of these (Si)GeSn epilayers on Ge/Si(001) takes place mostly via edge dislocations rather than via threading dislocations. Furthermore, the indirect-to-direct bandgap transition was presented by means of temperature-dependent photoluminescence measurements. Strain relaxed, direct-gap Ge_0.875Sn_0.125 alloys grown on Si(001) substrates exhibited high modal gain values up to 110 cm⁻¹ enabling the first demonstration of lasing action in direct bandgap group IV Fabry-Perot cavities.