Study of Optical Performance and Structure of Yb/Al (1.5 wt.% Si) and Yb/Al (Pure) Multilayers Designed for the 73.6 nm Range

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Colleagues

In this study, multilayer films of Yb/Al designed to operate at a target wavelength of 73.6 nm were fabricated using pure aluminum and aluminum doped with 1.5 wt.% silicon layers.

The results obtained can make a positive contribution to the development of the research field. But the relevance and novelty of the research is not clearly described. New film structures were fabricated or new measurements were performed on known film structures.

 In my opinion, in order to improve the manuscript, it is advisable to take into account the following comments:

Abstract

1)    please state the novelty of your study;

2)    please state clearly the goal of your work.

1. Introduction

1)    state the relevance of your work. In particular, why is the 73.6 nm wavelength important?

2)    please state clearly the goal of your work.  

2. Measurements & Data analysis

1) it is advisable to supplement the section with information on the fabrication of film structures;

2) please indicate the measurement range and error of the ultraviolet reflectometer.

3. Results & Discussion

1)    Fig. 5 is absent;

2)    the theoretical reflectivity curves are absent;

3)    there is no indication of the wavelength at which the measurements shown in Fig. 4 were performed;

4)    what ideal is mentioned in: «However, it is crucial to acknowledge that the obtained values fall short of the theoretical ideal» (lines 165-166);

5)    the statement: «The relatively weaker crystallization of Al enhances diffusion with Yb, leading to a reduction in the crystallinity of Yb. The diffusion between Al and Yb counteracts the improvement in interfacial roughness resulting from the reduced crystallization of Al.» (lines 144-147) has no proven basis and may be nothing more than speculation.

4. Conclusion

1)    please indicate the novelty of your study, comparing the results with [18];

2)    please clarify the statement: «In summary, the introduction of Si, by finely tuning the structural properties of the multilayer films» (lines 196-197)

References

1. It’s advisable to extend the list with articles published in 2022-2024.

2. Please add description to [19].

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Editor

 

I read with interest this manuscript regarding the optical properties of pure and silicon-doped Yb/Al multilayers.

This is interesting work because it is intended for the characterization of materials in a spectral range where there is little experimental information.

The experimental part is well described and the experiments themselves seem to support the authors' conclusions well.

Despite this, there are numerous points that require modification and correction before the manuscript can be judged suitable for publication.

The first is that the authors should better describe how these films are produced. The details of thermal evaporation are important and should be clearly stated in the text and at least one reference should be added. The authors should better describe how these films are produced. Were they also produced using the thermal evaporation method? It is not clear and if so the experimental details must be clearly indicated in the text. Did the authors use the same method? What were the conditions? How did they control the thicknesses of the individual layers? By controlling the evaporation time? All this information is necessary to be able to imagine repeating their experiments. In table 1, the authors describe their multilayer sample, there are different materials. What is the deposition order? It can be guessed that SiC is the deepest one, but it must be said precisely. What is the role of the different thickness of the Yb and Al (or Al/Si) layers, if any? On page 1, line 39, the authors cite a work by Vidal that should be their reference number 18. This should be clearly stated there as well.

Authors, in general, need to pay more attention to references. The introduction is well written, for the general framework and the theoretical discussion and makes it clear what the problem they intend to address is and what the open problems are.

However, some statements require specific references, especially for the benefit of a reader who is inexperienced in the field. The sentence “Among lanthanide materials, ytterbium (Yb) has a lower absorption coefficient in the 55-90 nm range”, (line 37) must be supported by references, possibly more than one.

The same is for “The addition of a small percentage of silicon (Si) into aluminium (Al) can be an effective method to modify the crystalline structure of the Al layer in multilayer films” (line 42)

Furthermore, reflectance and reflectivity are not the same concept and authors must be very precise when using one or the other. In the experimental part, rightly, they measure the reflectivity, in the introduction they talk about reflectance. A definition of both might be useful.

Regarding the Scherrer equation (line 75), the authors assume the value of 0.89 for the constant K, which sounds very realistic (in accordance with their assumptions), but again a reference justifying this choice would be useful. A different value would provide slightly different results. However, the assumption of spherical grains does not seem unrealistic.

Concerning figure 1 (and in general for all the figures): the size and the quality should be improved. Authors should make them larger: It's a little tricky to read the numbers and units (in particular for the AFM images in figure 2). Also, for figure 1, the caption should be more precise. It is easy to imagine that S1 is the sample without silicon, while S4 could be the one with silicon, but it must be written clearly and precisely.

Figure 5 should be 4, because there are not five figures in the manuscript. While this is obviously a typo and can be easily fixed, the figure itself is not good.

The two curves are evidently experimental curves, in the text the authors say that "Fig. 5 provides the theoretical reflectivity curves as computed by the IMD (Integrated Munster Data) software", but there is no trace of these curves. Without them, it is not possible to compare the experimental data with the theoretically expected values. Nor it can be judge whether the theoretical assumptions are acceptable whether the authors' hypotheses regarding the results are correct.

This figure must be absolutely correct.

In any case, the authors attribute the discrepancies between the experimental results and the expected theoretical values to some factors. This seems realistic. However, among them they mention incipient oxidation. Oxidation of what? Of the Yb layer? Has any variation in the thicknesses or even the formation of a new layer been measured? This data could be useful.

Personally I think that the authors should make some efforts to try to fix these points. This would make the quality of the manuscript higher and make it suitable for publication.

I would invite them to do this additional work

 

 

 

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The draft is correctly written, and the results are very well described. However, the presented draft looks much more like a technical paper than a scientific one. (maybe the style is appropriate for applied science journals )

I advise the authors to extend the discussion and discuss the structure-activity relationship, i.e., the correlation between obtained results and physical models.

 

Author Response

Dear Editor and reviewers:

Thank you very much for your comments.

In the article, our objective was to enhance the reflectivity of multilayer films by incorporating silicon using magnetron sputtering. This approach effectively increased the reflectivity of the multilayer films. Techniques such as Grazing Incidence X-ray Reflectivity (GIXRR), X-ray Diffraction (XRD), and Atomic Force Microscopy (AFM) were employed to analyze the impact of silicon incorporation on the internal structure of Yb/Al multilayer films. The results of the tests were analyzed, and speculation was made on the mechanism of how silicon impurities enhance the film reflectivity, demonstrating a certain level of scientific rigor. We kindly request the reviewers and editors to consider publishing our article in the "Coating" journal.

 

Yours sincerely,

Runze Qi (for all co-authors)

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors Dear Editor
  I think that this revised version of the manuscript is much improved compared to before and that the authors responded positively to the observations/comments I made.   The bibliography is now acceptable, too and and in general I think that this article is now now worth publishing. As a final observation, however, I would like to suggest to the authors that in certain cases, such as in the part that states that oxidation occurs during the process, to highlight clearly that this is a hypothesis. The adjective "possible" would be helpful.  

 

Comments on the Quality of English Language

This manuscript is written in much more than acceptable English There are no particular linguistic problems.