Microstructure and Stress of Ni/C Multilayer Films Prepared by Reactive Sputtering

Round 1

Reviewer 1 Report

The manuscript entitled "Microstructure and stress of Ni/C multilayer films prepared by reactive sputtering" was reviewed. This work and as-obtained results are interesting. In this paper, an investigation into microstructure and stress of Ni/C multilayers deposited by reactive DC magnetron sputtering was performed using a nitrogen-argon gas mixture. The effects of the incorporation of nitrogen on the interfacial microstructures of Ni/C multilayers were studied by characterization techniques including grazing incidence X-ray reflectivity, high-resolution cross-sectional transmission electron microscopy, and selected area electron diffraction. The stress of Ni/C multi- layers was determined by a wafer curvature measurement. I have the following comments;

1. Please start the Abstract by a short introduction of the current problem(s) and the solution, based on the current study, in one or two lines.

2. Make sure all abbreviations are written out in full the first time used. This is particularly important in the abstract and in the conclusions, but work through the entire ms carefully from this perspective. For example; acronym all the experimental techniques should be introduced the first time in the text.

3. Abstract should have some numerical data.

4. Introduction writing part is not satisfactory. Need to be improved.

5. The idea of the research seems to be interesting but the set goals are not achieved. What the main significance of paper in comparison is of relates published works?

6. What is the innovation of this article? Please highlight it in the article.

7. “Grazing incidence X-ray reflectivity” results are discussed in an incomprehensible way; the authors must be rewritten and better explained.

8. I have read and evaluated the manuscript and in my opinion the submission does not yet sufficiently justify publication. Discuss the shortcomings of previous work and the gaps and how this work intends to fill those gaps. Related references should be cited:

- Biosensors and Bioelectronics, 178 (2021) 113017. Journal of Molecular Catalysis A: Chemical 238 (1-2) (2005) 215-222; Inorganic Chemistry Communications 8 (2) (2005) 174-177; Journal of Molecular Catalysis A: Chemical 201 (1-2) (2003) 43-54; Journal of Molecular Catalysis A: Chemical 186 (1-2) (2002) 101-107; Ultrasonics sonochemistry 39 (2017) 494-503; Journal of Industrial and Engineering Chemistry 21 (2015) 1301-1305; International journal of hydrogen energy 42 (2017) 5235-5245-

9. Discussion of results is weak and results of readability are not logic.

10. There are some typographical and grammatical errors in the manuscript. Hence, the manuscript should be carefully checked and necessary corrections should be done.

I recommend publication of this article after major revisions and would like to see the revised version of paper before publication.

Author Response

Good suggestion!

Author Response File: Author Response.pdf

Reviewer 2 Report

The submitted paper deals with the effect of the nitrogen content on the micro-structure and the residual stress state of Ni/C multilayer films. It’s an interesting experimental work. My main remarks are the followings:

1.The authors have to describe more analytically the applied method for measuring the residual stresses? In which depth from the coating surface, the residual stresses into the film structure were measured?

2. Have the authors conducted any mechanical testing for characterizing the adhesion between the coating and the substrate? Such results have to be presented for verifying their assertation concerning the effect of the nitrogen content on the film-substrate adhesion.

3. Have the authors measured the hardness of the produced coatings?

4. The section “Discussion” has to be enlarged.

Author Response

Good suggestion!

Author Response File: Author Response.pdf

Reviewer 3 Report

The language was easy to understand and very clear. The references are in a regular scientific journal format. However, some citations seem missing (see below comments). TEM images and the plots are publishable quality.

Authors have attempted to study the effects on the interfacial microstructures of Ni/C multilayers in the different N2 ratios using several characterization techniques. Authors claim that the periodic thickness below 3 nm was difficult and hardly few studies in that area.

This is a well written manuscript and can be published in the MDPI: Coatings if the below comments are addressed.

Here are a few comments:

  1.  No need to include “where the ratio is defined as the partial pressure of N2 to the total pressure in the bottle.” In the abstract.

  2.   Page 1 and 2 (Introduction).

  a. The reader may feel like enough literature survey is not provided by the authors explaining the prior study on “Ni/C multilayers with periodic thickness below 3 nm”

  b. Please include more references

  3.  Page 2, line 55

  a. Again, please include more references:

  b. Here are a few suggestions:

  i.      Itapu, S., Georgiev, D. G., Uprety, P., & Podraza, N. J. (2017). Modification of reactively sputtered NiOx thin films by pulsed UV laser irradiation. physica status solidi (a), 214(2), 1600414.

   ii.      Borra, V., Itapu, S., & Georgiev, D. G. (2017). Sn whisker growth mitigation by using NiO sublayers. Journal of Physics D: Applied Physics, 50(47), 475309.

  4. Page 3, line 110-111, If there is a reference showing how “The increasing in the number of Bragg peaks corelate with the smaller interface width for the reactively-sputtered samples”, that would be beneficial.

  5. Authors mentioned that the wafer curvature was measured before and after film deposition by using the Fizeau interferometer, will those values be included in the manuscript?

  6.  Also, what was the final thickness that was deposited on the quartz glass?

  7. Finally, what was the measured stress of the substrate before the deposition? Was it close to 438 MPa?

If the authors have made the necessary corrections and changes to the article. I think that this work is worth publishing in this journal.

Author Response

Good suggestion!

Author Response File: Author Response.pdf

Reviewer 4 Report

The latest reference in the manuscript is from 2015. This is like a report and not a research paper. Although the quality of research is good, it is not a stand-alone thing. It does not have much novelty. 

Author Response

Good suggestion!

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The submitted paper can be accepted for publication in the current form.

Author Response

Thanks for your advice!

Reviewer 4 Report

replace EDX with EDS

Also, please explain the wavey nature of lattice fringes in the HRTEM image and the smooth nature in case of nitrogen 

Author Response

Good suggestion!

Author Response File: Author Response.pdf