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Group IV nanowires: a versatile toolbox for nano-and optoelectronic device

Khan, M. B.; Echresh, A.; Ghosh, S.; Arora, H.; Chava, P.; Jazavandi Ghamsari, S.; Khan, M. M.; Steuer, O.; Prucnal, S.; Hübner, R.; Rebohle, L.; Zhou, S.; Helm, M.; Erbe, A.; Georgiev, Y.

The attractive properties of semiconductor nanowires (NWs) are making them an appealing platform for building a variety of nanoelectronic, optoelectronic, sensing, etc. devices. In the wide range of semiconductor NWs, the ones based on group IV elements deserve a special attention. Beside the extensively studied silicon (Si) and germanium (Ge), their alloys with tin (Sn) – GeSn and SiGeSn – are very promising because of a number of unique properties. Suitable Sn concentrations allow effective bandgap engineering as well as achieving high charge carrier mobility and even a direct Group IV semiconductor for optoelectronic applications. In such a way, the SiGeSn alloy system combines the flexibility of III/V compound semiconductors and heterostructures with the mobility gain of Ge/GaAs hybrid systems and the maturity of the Si processing technology. This makes it ideal for post-Si based nanoelectronic and optoelectronic applications, if SiGeSn heterostructures can successfully be integrated into the well-established Si fabrication platforms.

In this talk, the top-down fabrication of Si, Ge and alloy NWs with varying content of the different elements (Si1-x-yGeySnx) will first be presented. Then, their challenging structural and electrical characterisation will be discussed. Here, special attention will be paid to the transmission electron microscopy (TEM) as well as to the Hall Effect measurements using a novel six-contact Hall bar configuration with symmetric contact bars located opposite to each other. This configuration allows reliable evaluation of the electrical properties of even very small nanowires with widths down to 20-30 nm as well as quantification of such parameters as carrier concentration (n), Hall mobility (µH), and resistivity (ρ).

Finally, some innovative nanoelectronic devices based on the fabricated NWs will be reviewed, in particular junctionless nanowire transistors (JNTs) and reconfigurable field effect transistors (RFETs). Different configurations of such devices will be discussed together with their structural and electrical characterisation. A special focus will be put on Si JNTs for sensing application as well as on Si, Ge, SiGe, GeSn and SiGeSn JNTs and RFETs for digital logic.

Acknowledgments: This work was partially supported by the German Bundesministerium für Bildung und Forschung (BMBF) under the project "ForMikro": Group IV heterostructures for high performance nanoelectronic devices (SiGeSn NanoFETs), Project-ID: 16ES1075, and by the European Union’s Horizon 2020 Research and Innovation programme under the project RADICAL, Grant Agreement No. 899282. We gratefully acknowledge the HZDR Ion Beam Centre and nanofabrication facility NanoFaRo.

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Publ.-Id: 36380