High level active n + doping of strained germanium through co-implantation and nanosecond pulsed laser melting
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mja276.pdf
Description
Published version
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750.04 KB
Format
Adobe PDF
Checksum (MD5)
65184d773f5b0f07d4f636870ae5f9c7
Author(s)
Pastor, David
Gandhi, Hemi H
Monmeyran, Corentin P
Akey, Austin J
Milazzo, Ruggero
Cai, Yan
Napolitani, Enrico
Gwilliam, Russell M
Crowe, Iain F
Michel, Jurgen
Date Issued
2018
Journal
Journal of Applied Physics
Publisher
AIP Publishing
Version
Final published version
Abstract
© 2018 Author(s). Obtaining high level active n+ carrier concentrations in germanium (Ge) has been a significant challenge for further development of Ge devices. By ion implanting phosphorus (P) and fluorine (F) into Ge and restoring crystallinity using Nd:YAG nanosecond pulsed laser melting (PLM), we demonstrate 1020 cm-3 n+ carrier concentration in tensile-strained epitaxial germanium-on-silicon. Scanning electron microscopy shows that after laser treatment, samples implanted with P have an ablated surface, whereas P + F co-implanted samples have good crystallinity and a smooth surface topography. We characterize P and F concentration depth profiles using secondary ion mass spectrometry and spreading resistance profiling. The peak carrier concentration, 1020 cm-3 at 80 nm below the surface, coincides with the peak F concentration, illustrating the key role of F in increasing donor activation. Cross-sectional transmission electron microscopy of the co-implanted sample shows that the Ge epilayer region damaged during implantation is a single crystal after PLM. High-resolution X-ray diffraction and Raman spectroscopy measurements both indicate that the as-grown epitaxial layer strain is preserved after PLM. These results demonstrate that co-implantation and PLM can achieve the combination of n+ carrier concentration and strain in Ge epilayers necessary for next-generation, high-performance Ge-on-Si devices.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
MIT Materials Research Laboratory
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DOI of Published Version
https://doi.org/10.1063/1.5012512
