Preparation of NbAs Single Crystal by the Seed Growth Process
Round 1
Reviewer 1 Report
The authors described a novel technique of growing NbAs Weyl crystal by the CVT method. Does the quality of the achieve crystal is better than done by the usual growing approach? Which parameters are necessary to compare different growing procedure crystals?
In addition, graphs of your crystal photoresponse in Figure 4 are unclear. What have you tried to achieve by turning your laser on and off? What is the meaning of periodicity? Is I features inside photoresponse patterns are essential? Please improve the description in the text and also in the caption of Figure 4.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors Sun, Zhao, Huo, Liu, Xu, Hu, and Qiu have submitted a manuscript entitled " Preparation of NbAs single crystal by the seed growth process " to the journal Crystals of MDPI.
The introduction provides sufficient background and includes all relevant references. The research design is appropriate. The methods are adequately described. The results are clearly presented. Discussion of data and conclusions are adequately supported by the results.
English language and style are minor spell check required.
I do not detect plagiarism and I do not detect inappropriate citations.
In general, I do not see any ethical issues along the manuscript.
In terms of originality, significance of content, quality of presentation, scientific soundness, interest to the readers, I think that the manuscript can be promising for the journal Crystals, but it needs some major revisions.
1) The authors should discuss a bit more the type of device that they have fabricated. What is the geometry of the device? Wry Cr/Au electrodes and not other materials?
The authors could provide (perhaps in Figure 4) a sketch of the fabricated device and a sketch of the energetic scenario in the device.
2) In the IV of Figure 4b I suggest to put also grid lines and maybe an inset in which the region very close to 0 V and 0 mA is magnified. Is the device intercepting the x-axis at voltage V=0? Why? Perhaps the authors could explain a bit more the operation of the device.
3) The authors state that in Figure 2c and 2d they show the "Typical
XPS spectrum of Nb 3d and As 3d core level". Are the spectra of general samples with Nb and As or are these the spectra of the fabricated sample?
Perhaps the authors wanted to say that the peaks are typical of Nb and As.
4) Did the authors perform also UPS to study bands in the systems? This would be very interesting.
5) Perhaps the authors could give a wider overview on the employment of Weyl semimetals for photocurrent? What is the advantage?
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
REFEREE REPORT
on paper “Preparation of NbAs single crystal by the seed growth process”
by authors Yinchang Sun, Bojin Zhao, Zongju Huo, Hongjun Liu, Yongkuan Xu, Zhanggui Hu and Hailong Qiu,
submitted to Crystals
The paper “Preparation of NbAs single crystal by the seed growth process” is devoted to preparation and investigation of the NbAs single crystals. A bottom-seed CVT growth method was proposed for the large-size, high-quality single crystals fabrication. XRD, Raman spectroscopy, XPS, HAASF-STEM, TEM, EDX techniques were used for the samples characterization. The topic of this paper is an actual. The work is of scientific interest to the audience of the Crystals. The data are reliable and do not cause much doubt. Nevertheless, there are several points before the paper can be published. I hope that authors after major revisions can improve the paper and can publish it in Crystals.
- The Introduction part must be improved with new literature about single crystals and I suggest to use the following references (see and discuss:
https://doi.org/10.1016/j.jallcom.2021.161451;
https://doi.org/10.1038/s41598-018-24823-z).
- What is the novelty of the presented research?
- Why did you choose bottom-seed CVT growth method for the samples preparation? Its advantages?
- Where the description of the experimental facilities (XRD, XPS etc.) used in this work? This information is absent…
- All diffraction peaks should be marked in diffractogram.
- Fig. 3 – scale and description of pictures b and с don’t “read”. The resolution must be improved.
- Fig. 3 с performs the information about chemical composition (maps of elements) but again the information of the experimental technique is absent.
- I didn’t find the information about such single crystals practical applications.
- Part 2.2 – I think it will be better to place the Fig. 4 a in this part.
- English must be improved, because now there are some typos and grammatical errors.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
In my opinion, after corrections, this manuscript is ready for publication.
Reviewer 2 Report
The authors Sun , Zhao , Huo , Liu , Xu , Hu , and Qiu ahve submitted to Crystals a revised version of the manuscript entitled " Preparation of NbAs single crystal by the seed growth process ".
Together with the revised manuscript, they have submitted a response letter in which they have replied, point-to-point, to the comments of the reviewer.
The answers to all the comments are appropriate.
I just would like to comment to the answer at question 4 (about UPS): it is true the statement of the authors "conduction band and valence band intersect at Weyl point". However, far from Gamma point the badn structure becomes more complex. Thus, an angle resolved photo-electron spectroscopy woudl enrich the characterization. But this would be a cumbersome study.
In general, I am satisfied with the answers of the authors and I would like to recommend to the editorial board to consider such manuscript for publication.
Reviewer 3 Report
After careful evaluation I feel that revised version can be accepted.
