Au-rich filamentary behavior and associated subband gap optical absorption in hyperdoped Si
Author(s)
Yang, W.; Akey, A. J.; Smillie, L. A.; McCallum, J. C.; Macdonald, D.; Aziz, M. J.; Williams, J. S.; Mailoa, Jonathan P; Johnson, Benjamin C; Buonassisi, Anthony; ... Show more Show less
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Au-hyperdoped Si, synthesized by ion implantation and pulsed laser melting, is known to exhibit a strong sub-band gap photoresponse that scales monotonically with the Au concentration. However, there is thought to be a limit to this behavior since ultrahigh Au concentrations (> 1 × 10[superscript 20] cm[superscript −3]) are expected to induce cellular breakdown during the rapid resolidification of Si, a process that is associated with significant lateral impurity precipitation. This work shows that the cellular morphology observed in Au-hyperdoped Si differs from that in conventional, steady-state cellular breakdown. In particular, Rutherford backscattering spectrometry combined with channeling and transmission electron microscopy revealed an inhomogeneous Au distribution and a subsurface network of Au-rich filaments, within which the Au impurities largely reside on substitutional positions in the crystalline Si lattice, at concentrations as high as ∼ 3
at. %. The measured substitutional Au dose, regardless of the presence of Au-rich filaments, correlates strongly with the sub-band gap optical absorptance. Upon subsequent thermal treatment, the supersaturated Au forms precipitates, while the Au substitutionality and the sub-band gap optical absorption both decrease. These results offer insight into a metastable filamentary regime in Au-hyperdoped Si that has important implications for Si-based infrared optoelectronics.
Date issued
2017-12Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science; Massachusetts Institute of Technology. Department of Mechanical EngineeringJournal
Physical Review Materials
Publisher
American Physical Society (APS)
Citation
Yang, W., et al. “Au-Rich Filamentary Behavior and Associated Subband Gap Optical Absorption in Hyperdoped Si.” Physical Review Materials, vol. 1, no. 7, Dec. 2017. © 2017 American Physical Society
Version: Final published version
ISSN
2475-9953