Origin and photoluminescence of a shallow hydrogen-related donor in silicon
Abstract
Paramagnetic color centers in silicon are being investigated recently for use in quantum technologies. While the origin of most of the prominent photoluminescence (PL) lines are well understood, that is not the case for those connected to hydrogen, even though it is almost always present in silicon, e.g., shallow hydrogen-related donors (SHDs), but their atomic structure remains elusive. Recent experiments suggested connection between the SHDs and the so-called X and the Bi (or Xi) PL-lines. An SHD, termed the MT2 center, was tentatively assigned to a bistable, negative-U defect, arising due to the interaction of hydrogen with the self-interstitial complex I4. Using high-level density functional theory calculations, we investigate the interaction of hydrogen with self-interstitial complexes In. A shallow effective-mass-theory donor arises when hydrogen attacks a Si-Si bond in In, inserting itself as a bond-center interstitial (InHBC) in an exothermic reaction. We demonstrate this in the case of a single self-interstitial and of a complex of four. The latter I4HBC complex shows electronic, spin and PL properties remarkably close to MT2. We find that hydrogen in the presence of I4 follows the same behavior as in pristine silicon, i.e., it is a negative-U bistable defect, only detectable under illumination. In the I4HBC complex, H can hop via photo-assisted mechanism between equivalent BC sites of the I4 complex, leading to a motional averaged tetragonal symmetry as experimentally observed for MT2. The zero-phonon line is distinct from the X-line (attributed to the bare I4 complex), and falls well into the range of the Xi lines. Our results identify the I4H complex as a prototype for a class of SHDs, inferring that similar SHDs may arise, with the Xi lines as their PL fingerprints, when H attacks In clusters.
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BibTeX
@misc{han2026origin,
title = {{Origin and photoluminescence of a shallow hydrogen-related donor in silicon}},
author = {Miaomiao Han and Peter Deak and Bing Huang and Adam Gali},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.39623},
eprint = {2610.39623},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.39623},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Origin and photoluminescence of a shallow hydrogen-related donor in silicon
AU - Miaomiao Han
AU - Peter Deak
AU - Bing Huang
AU - Adam Gali
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.39623
UR - https://arxiv.org/abs/2610.39623
AB - Paramagnetic color centers in silicon are being investigated recently for use in quantum technologies. While the origin of most of the prominent photoluminescence (PL) lines are well understood, that is not the case for those connected to hydrogen, even though it is almost always present in silicon, e.g., shallow hydrogen-related donors (SHDs), but their atomic structure remains elusive. Recent experiments suggested connection between the SHDs and the so-called X and the B_i (or X_i) PL-lines. An SHD, termed the MT2 center, was tentatively assigned to a bistable, negative-U defect, arising due to the interaction of hydrogen with the self-interstitial complex I_4. Using high-level density functional theory calculations, we investigate the interaction of hydrogen with self-interstitial complexes In. A shallow effective-mass-theory donor arises when hydrogen attacks a Si-Si bond in I_n, inserting itself as a bond-center interstitial (I_nH_BC) in an exothermic reaction. We demonstrate this in the case of a single self-interstitial and of a complex of four. The latter I_4H_BC complex shows electronic, spin and PL properties remarkably close to MT2. We find that hydrogen in the presence of I_4 follows the same behavior as in pristine silicon, i.e., it is a negative-U bistable defect, only detectable under illumination. In the I_4H_BC complex, H can hop via photo-assisted mechanism between equivalent BC sites of the I_4 complex, leading to a motional averaged tetragonal symmetry as experimentally observed for MT2. The zero-phonon line is distinct from the X-line (attributed to the bare I_4 complex), and falls well into the range of the X_i lines. Our results identify the I_4H complex as a prototype for a class of SHDs, inferring that similar SHDs may arise, with the X_i lines as their PL fingerprints, when H attacks I_n clusters.
ER -