Behrle, R., Murphey, C. G. E., Cahoon, J. F., Barth, S., den Hertog, M. I., Weber, W. M., & Sistani, M. (2024). Understanding the electronic transport of Al-Si and Al-Ge nanojunctions by exploiting temperature-dependent bias spectroscopy. ACS APPLIED MATERIALS & INTERFACES, 16(15), 19350–19358. https://doi.org/10.1021/acsami.3c18674
Understanding the electronic transport of metal-semiconductor heterojunctions is of utmost importance for a wide range of emerging nanoelectronic devices like adaptive transistors, biosensors, and quantum devices. Here, we provide a comparison and in-depth discussion of the investigated Schottky heterojunction devices based on Si and Ge nanowires contacted with pure single-crystal Al. Key for the fabrication of these devices is the selective solid-state metal-semiconductor exchange of Si and Ge nanowires into Al, delivering void-free, single-crystal Al contacts with flat Schottky junctions, distinct from the bulk counterparts. Thereof, a systematic comparison of the temperature-dependent charge carrier injection and transport in Si and Ge by means of current-bias spectroscopy is visualized by 2D colormaps. Thus, it reveals important insights into the operation mechanisms and regimes that cannot be exploited by conventional single-sweep output and transfer characteristics. Importantly, it was found that the Al-Si system shows symmetric effective Schottky barrier (SB) heights for holes and electrons, whereas the Al-Ge system reveals a highly transparent contact for holes due to Fermi level pinning close to the valence band with charge carrier injection saturation due to a thinned effective SB. Moreover, thermionic field emission limits the overall electron conduction, indicating a distinct SB for electrons.
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Project title:
Metastable nanoscale solid solutions and their integration: I 5383-N (FWF - Österr. Wissenschaftsfonds)
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Project (external):
U.S. National Science Foundation Deutsche Forschungsgemeinschaft European Union’s Horizon 2020
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Project ID:
DMR-2121643 BA6595/1-1 ; BA6595/4-1 758385
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Research Areas:
Materials Characterization: 50% Surfaces and Interfaces: 50%