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arxiv: 2510.14012 · v1 · pith:6CMQFMUPnew · submitted 2025-10-15 · ❄️ cond-mat.mtrl-sci

CBVB-nH complexes as prevalent defects in metal-organic vapor-phase epitaxy-grown hexagonal boron nitride

Marek Maciaszek , Bart{\l}omiej Baur This is my paper

Pith reviewed 2026-05-18 06:39 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords hexagonal boron nitridedefectscarbonhydrogenMOVPEphotoluminescenceab initio calculationsquantum emitters
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The pith

CBVB-nH complexes form as stable defects in MOVPE-grown hBN due to electrostatic binding and explain emission peaks at 1.90 eV and 2.24 eV.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper uses ab initio calculations to show that complexes made of a carbon atom on a boron site and a hydrogen-passivated boron vacancy are energetically favorable in nitrogen-rich conditions when carbon and hydrogen are present. Their low formation energies come from the attraction between the positive carbon defect and the negative vacancy complex. This is relevant for MOVPE-grown samples because those growth conditions naturally include carbon, hydrogen, and many boron vacancies. The calculations also link these complexes to specific optical emissions seen in experiments on such samples.

Core claim

The formation of CBVB-nH complexes (n from 0 to 3) is energetically favorable under nitrogen-rich conditions in the presence of carbon and hydrogen. The low formation energies and high binding energies arise from the strong electrostatic attraction between the positively charged carbon substitutional defect (CB) and the negatively charged hydrogen-passivated boron vacancies (VB-nH). These complexes are particularly likely to form in MOVPE-grown samples. The optical properties are consistent with emission peaks at 1.90 eV and 2.24 eV from hole capture by negatively charged complexes.

What carries the argument

The CBVB-nH complex, consisting of a carbon atom substituting for boron adjacent to a boron vacancy passivated by n hydrogen atoms, which gains stability from electrostatic attraction between its charged components.

If this is right

  • These complexes should be prevalent in MOVPE-grown hBN samples due to the growth environment rich in carbon, hydrogen, and boron vacancies.
  • The observed photoluminescence peaks at 1.90 eV and 2.24 eV can be attributed to hole capture by negatively charged CBVB and CBVB-H complexes.
  • Controlling carbon and hydrogen incorporation during growth could tune the density of these optically active defects.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Identifying these as common defects suggests that growth recipes might be adjusted to minimize unwanted emissions or enhance desired quantum properties in hBN devices.
  • Similar defect complexes might appear in other growth methods if boron vacancies and impurities are present, warranting checks in different hBN samples.

Load-bearing premise

MOVPE growth produces a high density of boron vacancies together with carbon and hydrogen incorporation, making CBVB-nH complexes prevalent.

What would settle it

Measuring significantly lower concentrations of boron vacancies or carbon-hydrogen related defects in MOVPE hBN samples, or finding that the calculated optical transition energies deviate substantially from the observed 1.90 eV and 2.24 eV peaks.

Figures

Figures reproduced from arXiv: 2510.14012 by Bart{\l}omiej Baur, Marek Maciaszek.

Figure 1
Figure 1. Figure 1: Formation energies of simple defects (VB, VB-H, VB-2H, VB-3H, CB, and Hi) as a function of the Fermi level under (a) N-rich and (b) N-poor conditions. 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7 8 9 10 CB Hi VB -3H VB -2H VB formation energy (eV) Fermi level (eV) VB -H 0 1 2 3 4 5 6 0 2 4 6 8 10 12 H C i B VB -3H VB VB -2H VB -H formation energy (eV) Fermi level (eV) [PITH_FULL_IMAGE:figures/full_fig_p019_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Formation energies of CBVB-nH complexes as a function of the Fermi level under (a) N-rich and (b) N-poor conditions. 0 1 2 3 4 5 6 0 1 2 3 4 5 6 CBVB -3H CBVB -2H CBVB -H CBVB formation energy (eV) Fermi level (eV) 0 1 2 3 4 5 6 0 2 4 6 8 10 12 CBVB CBVB -H CBVB -2H CBVB -3H Fermi level (eV) formation energy (eV) [PITH_FULL_IMAGE:figures/full_fig_p020_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: CBVB-nH complexes in hBN. For CBVB-H and CBVB-2H, the most stable geometric configurations (i.e., those corresponding to the lowest energy) are shown. Blue spheres represent nitrogen atoms, pink – boron, brown – carbon, and orange – hydrogen [PITH_FULL_IMAGE:figures/full_fig_p021_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: (a) Configuration coordinate diagram describing optical emission following hole capture by negatively charged CBVB. (b) Calculated luminescence lineshape for hole capture by negatively charged CBVB, obtained using the single effective mode approach (with Gaussian smearing). -2 0 2 0 1 2 3 4 (0/-)=2.96 eV EZPL=2.69 eV (CBVB ) - (C +h BVB ) -+hb energy (eV) Q (amu0.5 A) o (CBVB )0 Eb=0.27 eV Eem=2.24 eV Ere… view at source ↗
read the original abstract

Optically active defects in hexagonal boron nitride (hBN) are promising candidates for active components in emerging quantum technologies, such as single-photon emitters and spin centers. However, further progress in hBN-based quantum technologies requires a deeper understanding of the physics and chemistry of hBN defects. In this work, we employ ab initio calculations to investigate the thermodynamic stability and optical properties of defect complexes involving carbon, boron vacancies, and hydrogen. We demonstrate that the formation of CBVB-nH complexes (n from 0 to 3) is energetically favorable under nitrogen-rich conditions in the presence of carbon and hydrogen. The low formation energies and high binding energies of these complexes arise from the strong electrostatic attraction between the positively charged carbon substitutional defect (CB) and the negatively charged hydrogen-passivated boron vacancies (VB-nH). These complexes are particularly likely to form in metal-organic vapor-phase epitaxy (MOVPE)-grown samples, where growth occurs in the presence of carbon and hydrogen and is accompanied by a high density of boron vacancies. The optical properties of CBVB-nH complexes are analyzed and compared to recent photoluminescence measurements on MOVPE-grown hBN samples. In particular, we investigate the origin of the emission peaks at 1.90 eV and 2.24 eV and demonstrate that both the energies and lineshapes are consistent with hole capture by negatively charged CBVB and CBVB-H complexes.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The manuscript uses ab initio DFT calculations to examine CBVB-nH complexes (n = 0–3) in hBN. It reports low formation energies and high binding energies under N-rich conditions arising from electrostatic attraction between CB+ and (VB-nH)−, argues that these complexes are prevalent in MOVPE-grown samples because of simultaneous carbon, hydrogen, and high boron-vacancy incorporation, and shows that hole-capture transitions at the negatively charged complexes reproduce the energies and lineshapes of the 1.90 eV and 2.24 eV photoluminescence peaks.

Significance. If the computational results hold, the work supplies a concrete, physically motivated assignment of two prominent emission lines to specific carbon–vacancy–hydrogen complexes, which would aid defect identification and engineering for hBN-based quantum emitters. The calculations are performed independently of the target PL data, avoiding circular fitting, and the electrostatic origin of the binding energies provides a transparent mechanism.

major comments (2)
  1. [Computational Methods] Computational Methods: supercell sizes, k-point meshes, exchange-correlation functional (PBE or hybrid), and convergence criteria for formation energies, binding energies, and optical transition energies are not stated. These parameters directly determine the reported low formation energies and the 1.90/2.24 eV matches and must be documented for reproducibility.
  2. [Introduction / Discussion] Introduction and Discussion sections: the assertion that MOVPE growth produces a high density of boron vacancies (thereby making CBVB-nH complexes prevalent) is presented without quantitative estimates of VB incorporation rates, kinetic barriers, or references to measured defect densities in MOVPE hBN. Thermodynamic stability alone does not establish prevalence if the kinetic supply of isolated VB is low.
minor comments (1)
  1. [Notation] Define the exact atomic composition of CBVB-nH for each n at first use to prevent ambiguity when discussing charge states and optical transitions.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments and positive assessment of the potential impact of our work. We address each major comment below and will revise the manuscript to improve clarity and completeness.

read point-by-point responses

  1. Referee: [Computational Methods] Computational Methods: supercell sizes, k-point meshes, exchange-correlation functional (PBE or hybrid), and convergence criteria for formation energies, binding energies, and optical transition energies are not stated. These parameters directly determine the reported low formation energies and the 1.90/2.24 eV matches and must be documented for reproducibility.

    Authors: We agree that these computational parameters must be explicitly documented to ensure reproducibility. In the revised manuscript we will insert a dedicated Computational Methods subsection that specifies the supercell sizes, k-point sampling, exchange-correlation functional employed, and all convergence criteria used for the formation energies, binding energies, and optical transition energies. revision: yes

  2. Referee: [Introduction / Discussion] Introduction and Discussion sections: the assertion that MOVPE growth produces a high density of boron vacancies (thereby making CBVB-nH complexes prevalent) is presented without quantitative estimates of VB incorporation rates, kinetic barriers, or references to measured defect densities in MOVPE hBN. Thermodynamic stability alone does not establish prevalence if the kinetic supply of isolated VB is low.

    Authors: We acknowledge that the current text does not supply quantitative estimates or direct citations for boron-vacancy densities in MOVPE hBN. In the revision we will add relevant literature references on defect incorporation during MOVPE growth and will clarify that the argument for prevalence rests on the simultaneous presence of carbon, hydrogen, and boron vacancies under typical MOVPE conditions rather than on thermodynamics alone. We will adjust the wording if quantitative data cannot be located. revision: partial

Circularity Check

0 steps flagged

No significant circularity; derivation rests on independent DFT computations.

full rationale

The paper derives thermodynamic stability, formation energies, binding energies, and optical transition energies for CBVB-nH complexes directly from ab initio DFT calculations under nitrogen-rich conditions. These quantities are computed from first-principles electronic structure and are compared to, rather than fitted against, the experimental photoluminescence peaks at 1.90 eV and 2.24 eV. No step reduces a prediction to a fitted input by construction, invokes a self-citation as the sole justification for a uniqueness claim, or renames a known result as a new derivation. The statement that MOVPE growth supplies high boron-vacancy densities is presented as contextual background rather than a computed output, and the central claims remain self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on standard DFT approximations for defect energetics and the premise that MOVPE conditions supply the necessary carbon, hydrogen, and boron vacancies.

axioms (1)
  • domain assumption Density-functional-theory total energies accurately predict relative formation energies and binding energies of point-defect complexes in hBN.
    Invoked implicitly when stating that formation is 'energetically favorable' and binding energies are 'high'.

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Forward citations

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Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Substitutional oxygen as the origin of the 3.5 eV luminescence in hexagonal boron nitride

    cond-mat.mtrl-sci 2026-02 unverdicted novelty 6.0

    Substitutional oxygen replacing nitrogen (ON) in hBN produces the 3.5 eV luminescence via hole capture, with a calculated emission energy of 3.63 eV and lineshape matching experiment.

Reference graph

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