Synergistic Control of Crystal Planes and Defects in CVD Single-Crystal Diamond: A Review of Growth Mechanisms and Frontier Applications

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Major revision. The manuscript has strong content and a good topic fit, but it needs (i) a clearer review methodology/scope, (ii) tighter/safer phrasing for strong claims (especially termination and HD), (iii) improved Table 1 with a few quantitative anchors, and also current application directions.

Main comments and questions:

1. Could you please clarify how the literature was selected for this review (databases used, time window, keywords, inclusion/exclusion criteria)?
2. Does the review cover all CVD approaches (MPCVD, HFCVD, heteroepitaxy), or mainly homoepitaxial MPCVD growth?
3. What is the main novelty of this review compared with existing reviews on CVD diamond and NV centers? Is it the plane–defect–device correlation or mainly the inclusion of very recent literature?
4. You state that the growth rate of (111) diamond is roughly one-tenth of (100). Could you clarify under which growth conditions this comparison applies and provide supporting references or ranges?
5. Several statements on surface termination (e.g., fluorine-terminated (110) eliminating surface states and spin noise) appear strong. Are these conclusions mainly based on DFT predictions or confirmed experimentally? Could this be clarified in the text?
6. In the section on hexagonal diamond (HD), the text suggests superior or comparable hardness to cubic diamond. Given the ongoing debate on phase purity and stacking faults, could the wording be softened or more carefully qualified?
7. For each “frontier application” claim, could you indicate clearly whether the supporting evidence is experimental, theoretical (DFT), or both? Here it is worth emphasizing that the application of CVD diamond windows as dielectric windows for fusion reactor applications lies outside the scope of the present discussion. See, for example: Kotomin, E. A., Kuzovkov, V. N., Lushchik, A., Popov, A. I., Shablonin, E., Scherer, T., & Vasil’chenko, E. (2024). The Annealing Kinetics of Defects in CVD Diamond Irradiated by Xe Ions. Crystals, 14(6), 546.
8. In Table 1, the (111) plane is described as having a relatively high growth rate under certain conditions, whereas earlier text emphasizes low growth rate. Could this apparent inconsistency be clarified?
9. Would it be possible to add approximate quantitative ranges (growth rate, roughness, defect density) to Table 1 to make the comparison more informative?
10. For Figure 1, could the caption explicitly state the practical guideline derived from the image (e.g., optimal miscut angle and its effect)?
11. For Figure 2, could you clarify whether the data correspond to bulk crystals or epilayers, measurement direction, and how this relates to device relevance?
12. In the (100) section, when discussing nitrogen/boron effects on mechanical properties, could you clarify whether these data correspond to bulk crystals or epilayers and which growth method was used?
13. You mention that (100) is not ideal for NV/SiV orientation. Could you add a quantitative comparison or an explicit reference supporting this statement?
14. In the (111) section, could you summarize the main practical take-home rules (e.g., optimal α range, key parameters) in a short bullet list for clarity?
15. Would it be useful to add a small schematic or summary table of dominant (111) defects and corresponding mitigation strategies?
16. For fluorine termination on (110), are there experimental demonstrations of improved NV coherence or charge stability, or is this mainly based on simulations?
17. In the high-index plane section, could you clarify how NV alignment performance on (113) compares quantitatively with (111) and (110)?
18. For hexagonal diamond, could you briefly summarize how phase identification was performed in the cited works (XRD, TEM, Raman) and the known limitations?

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editor,

In the manuscript titled “Synergistic Control of Crystal Planes and Defects in CVD Single-Crystal Diamond: Growth Mechanisms and Frontier Applications”, Li et al. present a short review supported by 99 references. The paper is well structured, follows a clear and traceable organization, and provides a general overview of single-crystal diamond and its properties as a function of crystallographic planes and defects. Based on the reviewers’ opinions, the paper is interesting and can be considered for publication after major revision.

1. The word “review” should be included in the title.
2. The similarity index is 28% and should be reduced to below 15%.
3. The authors discuss applications of single-crystal diamond for quantum sensing and information; however, the underlying physics of these applications and their coupling with diamond properties are not adequately explained. Please describe these aspects using quantum mechanical principles and relevant equations.
4. As this paper emphasizes material applications for quantum technologies, the main research centers and universities active in this field, along with their key achievements, should be introduced in a separate section. Please focus on institutes that utilize single-crystal diamond and/or related materials.
5. As a review paper, it is expected to include more than seven figures. I recommend that the authors include additional figures and avoid reducing visual content solely due to the time-consuming process of obtaining permissions.
6. An atomic configuration of diamond clearly illustrating the (100), (111), and (110) crystallographic planes is necessary. Please include such a figure and label the planes explicitly.
7. Figure 6 is overly complex. Could the authors simplify this figure?
8. In the “Conclusion and Outlook” section, could the authors introduce computational packages that may facilitate further studies in the context of future research?
9. Please add a historical timeline outlining the development of diamond crystal and its applications in quantum technologies.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

After a successful revision, this paper can be recommended for publication.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editor,

In the revised manuscript titled “Synergistic Control of Crystal Planes and Defects in CVD Single-Crystal Diamond: A Review of Growth Mechanisms and Frontier Applications,” Li et al. have addressed all of my concerns. I am now pleased to recommend this paper for publication.