24-27 November 2022
Karlsruhe Institute of Technology
Europe/Berlin timezone

Temperature dependence of Raman scattering of Ge and GeSn layers

26 Nov 2022, 16:00
2h
Foyer (KIT Campus South)

Foyer

KIT Campus South

KIT Campus map: https://www.kit.edu/campusplan/ Building: 30.22 Room: Foyer im 1. und 2. OG Address: Institute of Technology, Engesserstraße 7, 76131 Karlsruhe Coordinates: 49.01244, 8.41062
Poster Physics Posters Poster session

Speaker

Diana Ryzhak (IHP – Leibniz-Institut für innovative Mikroelektronik)

Description

Germanium (Ge) and GeSn materials are very promising candidates for complementary metal-oxide-semiconductor electronics and photonics applications due to their high electron mobility and the possibility to achieve direct bandgap by tuning composition or strain. These are excellent perspectives for devices such as lasers, light-emitting diodes, photodetectors, and modulators. The vibrational properties of these materials can be related to the high quality of the material required for applications, as well as to electron-phonon and phonon-phonon interactions. To this aim, Raman spectroscopy is a well-suited technique that provides non-destructive testing and detailed information about thermal expansion, and anharmonicity.
In this work, Raman spectroscopy was used to study Ge and GeSn layers, through the analysis of the spectra in terms of peaks position, width, and asymmetry of the lineshape. Temperature dependence was measured from 80 to 573 K and analyzed by a model that considers thermal expansion, anharmonicity of the vibrations, and strain.
Ge layers were grown by Chemical (CVD) and Physical (PVD) vapor deposition process. Narrow peaks in high-quality epitaxially CVD-grown layers that evolve with temperature increase were observed. In polycrystalline samples deposited on SiO2 by PVD, Ge peaks were asymmetric and two times wider than on the Si substrate. The polycrystalline samples have the strongest anharmonicity, although it does not differ from the crystalline materials by more than 15%.
In thin, compressively strained GeSn alloy layers, grown by CVD with Sn concentration in the range of 5%-14%, the anharmonicity is more significant than in the polycrystalline Ge, and independent of the Sn content. These results will assist future developments for optoelectronics and thermoelectrics in semiconductors in group-IV semiconductors.

Category Solid State (Experiment)

Primary author

Diana Ryzhak (IHP – Leibniz-Institut für innovative Mikroelektronik)

Co-authors

Agnieszka Anna Corley-Wiciak (IHP – Leibniz-Institut für innovative Mikroelektronik) Costanza Lucia Manganelli (IHP – Leibniz-Institut für innovative Mikroelektronik) Omar Concepción (Peter Grünberg Institute 9 (PGI-9) and JARA-Fundamentals of Future Information Technologies (JARA-FIT)) Marvin Hartwig Zoellner (IHP – Leibniz-Institut für innovative Mikroelektronik) Oliver Skibitzki (IHP – Leibniz-Institut für innovative Mikroelektronik) Dan Buca (Peter Grünberg Institute 9 (PGI-9) and JARA-Fundamentals of Future Information Technologies (JARA-FIT)) Giovanni Capellini ((1) IHP – Leibniz-Institut für innovative Mikroelektronik. (2) Dipartimento di Scienze, Università Roma Tre) Davide Spirito (IHP – Leibniz-Institut für innovative Mikroelektronik)

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