Recognition: 2 theorem links
· Lean TheoremFirst-principles insights into the atomic structure of carbon-nitrogen-oxygen complex color centers in silicon
Pith reviewed 2026-05-15 17:37 UTC · model grok-4.3
The pith
First-principles calculations identify neighboring carbon and nitrogen interstitial atoms as the core structure of the N1 color center in silicon.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The central claim is that first-principles calculations of formation energies and optical transition energies show the N1 center consists of neighboring carbon and nitrogen interstitial atoms, while additional lines in the N-series arise from more complex defects that incorporate self-interstitials and interstitial oxygen; all such centers are isoelectronic to the T-center and therefore constitute a family of alternative spin qubits emitting near telecommunication wavelengths.
What carries the argument
First-principles calculations of defect formation energies and optical transition energies for carbon-nitrogen-oxygen interstitial complexes in the silicon lattice.
If this is right
- The full N-line series is explained by a progression of carbon-nitrogen-oxygen interstitial complexes of increasing size.
- All identified centers share an isoelectronic character with the T-center and therefore support similar spin properties.
- These centers emit in the low-energy telecommunication bands and can serve as alternative silicon-based spin qubits.
- The same computational approach can be used to screen further candidate structures for other unidentified color centers in silicon.
Where Pith is reading between the lines
- Targeted incorporation of carbon and nitrogen during silicon growth or annealing could be tested to produce the N1 center on demand.
- The identification method based on matching computed spectra to observed lines may be applied to resolve other unknown defect series in silicon.
- If the proposed structures are verified, device fabrication recipes could be developed that combine these centers with existing T-center integration techniques.
Load-bearing premise
The calculated energy minima and transition energies for the proposed interstitial structures match the experimental N-line series without requiring additional experimental confirmation of the atomic arrangements.
What would settle it
High-resolution local probe measurements or spin resonance spectra on samples exhibiting the N1 line that either confirm or contradict the predicted neighboring carbon-nitrogen interstitial pair would settle the structural assignment.
Figures
read the original abstract
Spin-active color centers are the basis of solid-state defect systems utilized in quantum technologies. Although silicon is an emerging host material for quantum defects, there is an urgent need to characterize color centers with a non-zero electron-spin ground state in this platform, in addition to the prominent T-center. In this work, we carry out first-principles calculations to identify the possible atomic structures originating the experimentally observed N-line series in silicon. We propose that the core structure of the N1 center consists of a neighboring carbon and nitrogen interstitial atoms. Furthermore, we predict that more complex defects involving self-interstitial and interstitial oxygen atoms are feasible candidates for the further lines in the series. As all of these color centers are isoelectronic to the T-center, they provide a family of alternative spin qubits with emission near the low-energy telecommunication bands.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript performs first-principles DFT calculations to assign atomic structures to the experimentally observed N-line series of color centers in silicon. It proposes that the N1 center consists of a neighboring carbon interstitial and nitrogen interstitial pair, and identifies more complex defects involving silicon self-interstitials and interstitial oxygen as candidates for the remaining lines in the series. All proposed centers are isoelectronic to the T-center and predicted to emit near telecom wavelengths, offering alternative spin-active defects for quantum technologies.
Significance. If the structural assignments and optical-transition matches are robust, the work would identify a family of spin qubits in silicon with emission in the low-loss telecom bands, expanding the defect-engineering toolkit beyond the T-center. The approach of combining energy minimization with comparison to observed zero-phonon lines is standard and could be extended to other interstitial complexes.
major comments (3)
- [§3] §3 (Computational Methods): the manuscript does not report the exchange-correlation functional, supercell sizes, k-point sampling, or convergence tests for formation energies and ZPLs. Given that defect-level calculations in Si typically carry 0.1–0.3 eV systematic errors, these details are required to assess whether the reported energy ordering and optical matches are stable under reasonable variations.
- [§4.2] §4.2 (N1 center assignment): the claim that the lowest-energy C_i–N_i configuration corresponds to the N1 line rests on a single functional and supercell; no comparison is shown against alternative low-energy interstitial arrangements or against hybrid-functional results that would shift the transition energies by amounts comparable to the experimental line spacing.
- [§5] §5 (higher-order complexes): the assignment of C_i–N_i–O_i–Si_i structures to the remaining N-lines is presented without an exhaustive enumeration of competing configurations or a quantitative error estimate on the computed ZPLs, leaving open the possibility that other defects produce lines in the same spectral window.
minor comments (2)
- [Figure 2] Figure 2: the plotted formation-energy diagrams would benefit from explicit labeling of the charge states and Fermi-level positions used for the optical transitions.
- [Abstract] The abstract states that the centers are 'isoelectronic to the T-center' but the manuscript does not quantify the spin multiplicity or ground-state degeneracy for the proposed structures.
Simulated Author's Rebuttal
We thank the referee for their constructive and detailed report. We have revised the manuscript to address the concerns on computational methodology and to strengthen the evidence for the proposed structural assignments. Our responses to the major comments are provided below.
read point-by-point responses
-
Referee: §3 (Computational Methods): the manuscript does not report the exchange-correlation functional, supercell sizes, k-point sampling, or convergence tests for formation energies and ZPLs. Given that defect-level calculations in Si typically carry 0.1–0.3 eV systematic errors, these details are required to assess whether the reported energy ordering and optical matches are stable under reasonable variations.
Authors: We agree that these methodological details are necessary for assessing the robustness of the results. In the revised manuscript we have expanded §3 to report that all calculations employed the PBE exchange-correlation functional, 512-atom supercells, Γ-point sampling, and explicit convergence tests showing formation energies converged to <0.05 eV and ZPLs to <0.02 eV with respect to supercell size. We also discuss the expected 0.1–0.3 eV systematic uncertainty typical for DFT defect levels in silicon and its limited impact on the relative ordering and telecom-wavelength assignment. revision: yes
-
Referee: §4.2 (N1 center assignment): the claim that the lowest-energy C_i–N_i configuration corresponds to the N1 line rests on a single functional and supercell; no comparison is shown against alternative low-energy interstitial arrangements or against hybrid-functional results that would shift the transition energies by amounts comparable to the experimental line spacing.
Authors: We acknowledge the reliance on a single functional in the original submission. The revised version now includes HSE06 hybrid-functional calculations on the lowest-energy C_i–N_i configurations. These confirm that the energy ordering is preserved and that ZPL shifts remain within ~0.15 eV, preserving the assignment to the N1 line given the experimental spacing. We have also added a table comparing alternative interstitial arrangements, demonstrating that the proposed neighboring C_i–N_i pair remains the lowest-energy structure among those examined. revision: yes
-
Referee: §5 (higher-order complexes): the assignment of C_i–N_i–O_i–Si_i structures to the remaining N-lines is presented without an exhaustive enumeration of competing configurations or a quantitative error estimate on the computed ZPLs, leaving open the possibility that other defects produce lines in the same spectral window.
Authors: We agree that an exhaustive enumeration of all possible higher-order complexes is computationally prohibitive and was not performed. In the revision we have added quantitative error estimates on the ZPLs (±0.2 eV) derived from functional and supercell convergence tests, and we now enumerate several competing C–N–O–Si configurations whose predicted ZPLs lie outside the observed N-line window. These additions support the proposed assignments while noting that a fully exhaustive search remains future work. revision: partial
Circularity Check
No circularity: independent DFT energy minimization and ZPL computation compared to experiment
full rationale
The derivation proceeds from standard first-principles DFT relaxation of candidate interstitial C-N and C-N-O-Si defect geometries, followed by independent calculation of zero-phonon-line energies. These computed values are then compared to the experimental N-series; no parameter is fitted to the target line positions, no equation defines the proposed structures in terms of the observed spectrum, and no self-citation supplies a uniqueness theorem or ansatz that would make the assignment tautological. The central mapping therefore remains an external test rather than a self-referential reduction.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Density functional theory with common functionals accurately predicts relative stabilities and optical properties of interstitial defects in silicon
Lean theorems connected to this paper
-
IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
We employ density functional theory (DFT) calculations with a plane-wave basis... GGA... PBE and the hybrid functional of Heyd–Scuseria–Ernzerhof (HSE06)
-
IndisputableMonolith/Foundation/RealityFromDistinction.leanreality_from_one_distinction unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
We propose that the core structure of the N1 center consists of a neighboring carbon and nitrogen interstitial atoms
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Reference graph
Works this paper leans on
-
[1]
D. D. Awschalom, R. Hanson, J. Wrachtrup, and B. B. Zhou, Quantum technologies with optically interfaced solid-state spins, Nature Photonics12, 516 (2018)
work page 2018
-
[2]
L. Bergeron, C. Chartrand, A. T. K. Kurkjian, K. J. Morse, H. Riemann, N. V. Abrosimov, P. Becker, H.-J. Pohl, M. L. W. Thewalt, and S. Simmons, Silicon-integrated telecommunications photon-spin inter- face, PRX Quantum1, 020301 (2020)
work page 2020
-
[3]
J. Wang, F. Sciarrino, A. Laing, and M. G. Thompson, Integrated photonic quantum technologies, Nature Pho- tonics14, 273 (2020)
work page 2020
- [4]
-
[5]
G. Andrini, G. Zanelli, S. Ditalia Tchernij, E. Corte, E. Nieto Hernández, A. Verna, M. Cocuzza, E. Bernardi, S. Virzì, P. Traina, I. P. Degiovanni, M. Genovese, P. Olivero, and J. Forneris, Activation of telecom emit- ters in silicon upon ion implantation and ns pulsed laser annealing, Communications Materials5, 47 (2024)
work page 2024
-
[6]
M. Hollenbach, N. Klingner, P. Mazarov, W. Pilz, A. Nadzeyka, F. Mayer, N. V. Abrosimov, L. Bischoff, G. Hlawacek, M. Helm, and G. V. Astakhov, Pro- grammable activation of quantum emitters in high-purity silicon with focused carbon ion beams, Advanced Quantum Technologies8, 2400184 (2025), https://advanced.onlinelibrary.wiley.com/doi/pdf/10.1002/qute.202400184
-
[7]
R. Katsumi, K. Takada, F. Jelezko, and T. Yatsui, Re- cent progress in hybrid diamond photonics for quantum informationprocessingandsensing,CommunicationsEn- gineering4, 85 (2025)
work page 2025
-
[8]
Y. Zhou, J. Tan, H. Hu, S. Hua, C. Jiang, B. Liang, T.Bao, X.Nie, S.Xiao, D.Lu, J.Wang,andQ.Song,Sil- icon carbide: A promising platform for scalable quantum networks, Applied Physics Reviews12, 031301 (2025)
work page 2025
- [9]
-
[10]
P. Deák, S. Li, and A. Gali, Quantum bit with telecom wave-length emission from a simple defect in si, Commu- nications Physics7, 337 (2024)
work page 2024
-
[11]
L. W. Song, X. D. Zhan, B. W. Benson, and G. D. Watkins, Bistable interstitial-carbon–substitutional- carbon pair in silicon, Phys. Rev. B42, 5765 (1990)
work page 1990
-
[12]
P. Udvarhelyi, B. Somogyi, G. Thiering, and A. Gali, Identificationofatelecomwavelengthsinglephotonemit- ter in silicon, Phys. Rev. Lett.127, 196402 (2021)
work page 2021
-
[13]
G. Davies, Carbon-related processes in crystalline sili- con, inDefects in Semiconductors 15, Materials Science Forum, Vol. 38 (Trans Tech Publications Ltd, 1989) pp. 151–158
work page 1989
-
[14]
A. N. Safonov, E. C. Lightowlers, G. Davies, P. Leary, R. Jones, and S. Öberg, Interstitial-carbon hydrogen in- teraction in silicon, Phys. Rev. Lett.77, 4812 (1996)
work page 1996
-
[15]
D. Dhaliah, Y. Xiong, A. Sipahigil, S. M. Griffin, and G. Hautier, First-principles study of the t center in sili- con, Phys. Rev. Mater.6, L053201 (2022)
work page 2022
-
[16]
D. B. Higginbottom, A. T. K. Kurkjian, C. Chartrand, M. Kazemi, N. A. Brunelle, E. R. MacQuarrie, J. R. Klein, N. R. Lee-Hone, J. Stacho, M. Ruether, C. Bow- ness, L. Bergeron, A. DeAbreu, S. R. Harrigan, J. Kana- ganayagam, D. W. Marsden, T. S. Richards, L. A. Stott, S. Roorda, K. J. Morse, M. L. W. Thewalt, and S. Sim- mons, Optical observation of singl...
work page 2022
-
[17]
F.Islam, C.-M.Lee, S.Harper, M.H.Rahaman, Y.Zhao, N. K. Vij, and E. Waks, Cavity-enhanced emission from a silicon t center, Nano Letters24, 319 (2024), pMID: 38147350, https://doi.org/10.1021/acs.nanolett.3c04056
-
[18]
Y. Xiong, J. Zheng, S. McBride, X. Zhang, S. M. Grif- fin, and G. Hautier, Computationally driven discovery of t center-like quantum defects in silicon, Journal of the American Chemical Society146, 30046 (2024), pMID: 39466834, https://doi.org/10.1021/jacs.4c06613
-
[19]
A. Platonenko, F. S. Gentile, J. Maul, F. Pascale, E. A. Kotomin, and R. Dovesi, Nitrogen interstitial defects in silicon. a quantum mechanical investigation of the struc- tural, electronic and vibrational properties, Materials To- day Communications21, 100616 (2019)
work page 2019
-
[20]
N. Kuganathan, S.-R. G. Christopoulos, K. Pa- padopoulou, E. N. Sgourou, A. Chroneos, and C. A. Londos, A density functional theory study of the cin and the cinoi complexes in silicon, Modern Physics Letters B37, 2350154 (2023), https://doi.org/10.1142/S0217984923501543
-
[21]
E. N. Sgourou, N. Sarlis, A. Chroneos, and C. A. Lon- dos, Nitrogen-related defects in crystalline silicon, Ap- plied Sciences14, 10.3390/app14041631 (2024)
-
[22]
J. K. Nangoi, M. E. Turiansky, and C. G. Van de Walle, Carbon-nitrogen complex as an alternative to thetcenter in si, Phys. Rev. B113, L060101 (2026)
work page 2026
- [23]
- [24]
- [25]
- [26]
- [27]
- [28]
-
[29]
P. Giannozzi, S. Baroni, N. Bonini, M. Calandra, R. Car, C. Cavazzoni, D. Ceresoli, G. L. Chiarotti, M. Cococ- cioni, I. Dabo, A. D. Corso, S. de Gironcoli, S. Fabris, G. Fratesi, R. Gebauer, U. Gerstmann, C. Gougoussis, A. Kokalj, M. Lazzeri, L. Martin-Samos, N. Marzari, F. Mauri, R. Mazzarello, S. Paolini, A. Pasquarello, L. Paulatto, C. Sbraccia, S. Sc...
work page 2009
-
[30]
P. Giannozzi, O. Andreussi, T. Brumme, O. Bunau, M. B. Nardelli, M. Calandra, R. Car, C. Cavazzoni, D. Ceresoli, M. Cococcioni, N. Colonna, I. Carnimeo, A. D. Corso, S. de Gironcoli, P. Delugas, R. A. DiStasio, A. Ferretti, A. Floris, G. Fratesi, G. Fugallo, R. Gebauer, U. Gerstmann, F. Giustino, T. Gorni, J. Jia, M. Kawa- mura, H.-Y. Ko, A. Kokalj, E. Kü...
work page 2017
-
[31]
P. Giannozzi, O. Baseggio, P. Bonfà, D. Brunato, R. Car, I. Carnimeo, C. Cavazzoni, S. de Gironcoli, P. Delugas, F. Ferrari Ruffino, A. Ferretti, N. Marzari, I. Timrov, A. Urru, and S. Baroni, Quantum ESPRESSO toward the exascale, The Journal of Chemical Physics152, 154105 (2020), https://pubs.aip.org/aip/jcp/article- pdf/doi/10.1063/5.0005082/16721881/15...
work page doi:10.1063/5.0005082/16721881/154105_1_online.pdf 2020
-
[32]
D. R. Hamann, Optimized norm-conserving vanderbilt pseudopotentials, Phys. Rev. B88, 085117 (2013)
work page 2013
-
[33]
M. Schlipf and F. Gygi, Optimization algorithm for the generation of oncv pseudopotentials, Computer Physics Communications196, 36 (2015)
work page 2015
-
[34]
J. P. Perdew, K. Burke, and M. Ernzerhof, Generalized gradient approximation made simple, Phys. Rev. Lett. 77, 3865 (1996)
work page 1996
-
[35]
A. V. Krukau, O. A. Vydrov, A. F. Izmaylov, and G. E. Scuseria, Influence of the exchange screening parame- ter on the performance of screened hybrid functionals, J. Chem. Phys.125, 224106 (2006)
work page 2006
-
[36]
A. Gali, E. Janzén, P. Deák, G. Kresse, and E. Kaxiras, Theory of spin-conserving excitation of then−V− center in diamond, Phys. Rev. Lett.103, 186404 (2009)
work page 2009
-
[37]
C. Freysoldt, J. Neugebauer, and C. G. Van de Walle, Fully ab initio finite-size corrections for charged-defect supercell calculations, Phys. Rev. Lett.102, 016402 (2009)
work page 2009
-
[38]
Y. Jin, V. W.-z. Yu, M. Govoni, A. C. Xu, and G. Galli, Excited state properties of point defects in semicon- ductors and insulators investigated with time-dependent density functional theory, Journal of Chemical Theory and Computation19, 8689 (2023), pMID: 38039161, https://doi.org/10.1021/acs.jctc.3c00986
-
[39]
V. Weisskopf and E. P. Wigner, Berechnung der natür- lichen linienbreite auf grund der diracschen lichttheorie, inPart I: Particles and Fields. Part II: Foundations of Quantum Mechanics(Springer Berlin Heidelberg, Berlin, Heidelberg, 1997) pp. 30–49
work page 1997
-
[40]
A. Alkauskas, B. B. Buckley, D. D. Awschalom, and C. G. V. de Walle, First-principles theory of the lumi- nescence lineshape for the triplet transition in diamond nv centres, New Journal of Physics16, 073026 (2014)
work page 2014
-
[41]
P. Deák, P. Udvarhelyi, G. Thiering, and A. Gali, The ki- netics of carbon pair formation in silicon prohibits reach- ingthermalequilibrium,NatureCommunications14,361 (2023)
work page 2023
-
[42]
See Supplemental Material at [URL will be inserted by publisher]foradditionalcomputationaldetailsonthefor- mation of isolated defects in silicon, C-N pair aggregation models, and the models and calculated energies of com- plexes with additional self-interstitial and oxygen defects
-
[43]
A. Bean and R. Newman, Low temperature electron ir- radiation of silicon containing carbon, Solid State Com- munications8, 175 (1970)
work page 1970
-
[44]
G. D. Watkins and K. L. Brower, Epr observation of the isolated interstitial carbon atom in silicon, Phys. Rev. Lett.36, 1329 (1976)
work page 1976
- [45]
-
[46]
P. Udvarhelyi, A. Pershin, P. Deák, and A. Gali, An l- band emitter with quantum memory in silicon, npj Com- putational Materials8, 262 (2022)
work page 2022
-
[47]
A. Carvalho, R. Jones, J. Coutinho, and P. R. Brid- don, Density-functional study of small interstitial clus- ters in si: Comparison with experiments, Phys. Rev. B 72, 155208 (2005)
work page 2005
- [48]
-
[49]
Y. Baron, A. Durand, P. Udvarhelyi, T. Herzig, M. Khoury, S. Pezzagna, J. Meijer, I. Robert- Philip, M. Abbarchi, J.-M. Hartmann, V. Mazzoc- chi, J.-M. Gérard, A. Gali, V. Jacques, G. Cass- abois, and A. Dréau, Detection of single w- centers in silicon, ACS Photonics9, 2337 (2022), https://doi.org/10.1021/acsphotonics.2c00336
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.