Analysis of Te Inclusion Striations in (Cd,Zn)Te Crystals Grown by Traveling Heater Method

Round 1

Reviewer 1 Report

p.3 : “ it is worth noting” not “nothing” - the word is misspelled.

p.3.” the distribution is random” not “randomly”

p.3. “The total concentrations of the Te inclusions in the seed region and the grown crystal region are 5.8 × 104cm-3 and 3.9 × 104cm-3, respectively. …The inclusions in the seed show lower density, but larger size when compared to the ones in the grown crystal.”

There is a contradiction in these statements. I suppose that according to these data density of Te inclusions is lower after THM growth as compared to the seed.

p.5. “Almost 7 times inclusions”

“Almost 7 times  more inclusions”

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

General comments on paper: 

Well-written and researched paper. Was a very enjoyable read and made its points clear. Nice work.

Specific comments on paper: 

Line 30: ‘Forced convection, such as the application of a static magnetic field, 30 rotating magnetic field (RMF) and accelerated crucible rotation technique, is therefore in-31 duced to suppress the natural convection and consequently to improve the homogeneity 32 in the solution zone’

Comment: Please provide references for these techniques having been used for THM growth of CdZnTe.

 

Line 35: ‘Therefore, microgravity offers a unique opportunity to study the growth 35 mechanism and improve the technique to grow homogeneous crystals.’

Comment: Although not strictly necessary, a further elaboration on the experimental design, parameters of interest, and focus of the space based vs ground based comparison (objectives of the larger study) would likely be of interest to the reader. It is not clear to the reviewer if the aim of the larger study is primarily focused on the formation of Te inclusions as is the focus of this specific paper.

 

Line 57: ‘The diameter of typical Te inclu-57 sions is 1 to 30μm. Te inclusions with diameter larger than 10 μm can dramatically affect 58 the performance and efficiency of the detector, while the detector resolution is better when 59 the inclusions size is smaller [21,22]’

Comment: Please specify the resolution referred to here and provide some guidance regarding what level of resolution degradation has been reported previously leading to this statement. It would be the reviewers assumption that the resolution referred to would be the energy resolution as opposed to for example spatial resolution.

 

General comment Section 2 Material and Methods: A bit further elaboration on the growth setup and process, alternatively reference to existing publication describing this, would be helpful for the reader, but not critical.

 

Table 1: Heater Temperature values.

Comment: Unclear to the reviewer what the temperatures here refer to and why sample F1-03 have three temperature values. Are these temperature zones used throughout the growth, the variation observed in the heater?

 

Line 95: ‘To compare the seed and the grown crystal, an area near the interface in F1-03 was 95 evaluated and quantification of Te inclusion density was performed. Figure 2 shows that 96 some larger inclusions are homogeneously distributed in the seed, while there are more 97 inclusions in the grown crystal with considerably smaller sizes.’

Comment: Showing the different regions (Seed and grown crystal) on the images in figure 1 that correlates to the imaged area shown in figure 2 would be helpful.

 

Line 100: It is 100 worth nothing that the inclusion distribution in the seed (Figure 3a, Supplementary file 1) 101 is randomly…

Comment: I believe you meant noting as opposed to nothing.

 

Figure 3: Regarding the histograms (c and d)

Comment: Would suggest, although not strictly necessary, to include the entries in both of the histograms for the readers ease of evaluation of the number of inclusions in the two regions.

 

Line 132: ‘With the assumption that Te inclusions have near spherical geometry, the atomic density of the excess Te can be calculated 133 using the following equation’

Comments: It is generally accepted that inclusion have a tendency to form in pyramid shape patters. Perhaps simplification would be a better phrasing then assumption for the shape of the inclusions used in the mathematical description.

 

Line 148: ‘The atomic density of the other 148 two ingots is comparably stable and it increases slightly at the ends of the ingots..’

Comments: while I would agree a slight increase can be seen for sample F1-03, I have a hard time seeing this effect in sample F1-02.

 

Line 163: ‘This phenomenon observed in all crystals in this work is 163 sketched and represented in Figure 6’

Comment: The periodicity of the grown region of the cartoon would suggest a uniform periodicity, while the images and the histogram in figure 8, if I understand it correctly, suggest there are at least 5 significant levels of periodicity observed in this sample. The cartoon should reflect this or highlight in the figure text that it is only intending to highlight one feature of the striation (the concave interface observed in sample F1-02).

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Thank you for providing me the opportunity to contribute as a reviewer. Following are my thoughts regarding the manuscript titled "Analysis of Te Inclusion Striations in (Cd,Zn)Te Crystals Grown by Travelling Heater Method" by Jiaona Zou et al., as submitted to Crystals (ID: 1224502).

In the current work the authors use the established THM to grow CZT crystals, and study certain kinds of defects arising during the procedure. Specifically, they report on the inclusions distribution (L 13), they attempt to unveil potential correlations with growth parameters (L 15) and plan to utilize the outcomes in preparation for upcoming experiments in micro-gravity (L 46). Therefore, and given the importance of CZT (L 21) and THM (L 25), I consider this work to be well within the scope of Crystals and to certainly be of interest to the readers of this journal.

Nevertheless, several issues require to be addressed by the authors; including, first and foremost, that the fulfillment of the initial Aims of this work remains questionable.

Starting from the investigation for potential correlation between temperature and striations, the authors Fourier-transform both of them, plot the results in Figure 8 and base the fulfillment of one of the main initial Aims of the manuscript on the phrase “coincide with each other to some extent” (L 206). Which is a rather arbitrary argument, inasmuch as the two peaks have ~20μm distance, ~20μm FWHM and no error data is given. All temperature readings lack the equipment uncertainties, by the way. Regarding the inclusions distribution: how is the initial curve formed, which is then Fourier-transformed to provide the red one in Figure 8? Is any averaging or fitting applied on the distribution data, and what errors does this introduce in the calculations?

Similarly subjective is the argument “High density of Te inclusions tends to accumulate as the temperature changes periodically, where are indicated with pale red color.” (L 215-7), which I find difficult to follow, since the “correlation” in Figure 9 is rather intuitive and not obvious.

In respect of the other initial Aim of this work, that of the upcoming microgravity experiments, it would be of help if the authors could define exactly which “technological parameters” (L 46) were determined as a result of the present experiments.

Another issue that would worth elaborating on, is the Materials & Methods section. Authors could provide more details, such as manufacturers and models of the equipment used (THM, RMF, IR, etc). Please also state the crystals’ diameter; this important spec is nowhere stated, nor is clearly visible in Figure 1a.

Besides, supplying the supplementary files in the Results section is highly appreciated. Eventually, in talking about temperatures (L 192-6), a series of mistakes were found after examining the respective file: “high degree of fluctuations is observed in that of the ampoule temperature, especially in ΔT5/Δt and ΔT6/Δt.” In fact, T4 and T5 show the max fluctuations (up to 8.75 °C/min for T4 and 5 °C/min for T5), whereas ΔT6/Δt max is 2.5 °C/min. Also, “T5 and T6 have the highest temperature” is not true, since T3 and T4 show the highest temperatures; besides, they sit closer to the heater.

Beyond the above broad comments, the following specific ones should be addressed as well.

L 38: Please check “FONTON-M” for typing errors

Table 1: Please explain 1,110-1,100-1,110 °C for F1-03

L 84, 91: Please consider using “slice” instead of “slide”

L 101: Please correct “nothing” to “noting”

L 131: “To take into account of” Please check expression

L 148: “unexpected power abortion” Please check wording

L 158: Section numbering is 3.3

L 173-4: “influence the uniformity of charge transport uniformity. More uniform distributed” Please check expression

L 269: “100 Mm” please check case

Supplementary files 1 and 2:
please define f, l, zi, yt, yp, xt, xp

Supplementary file 3:
data for F1-01: Please check units for X position; cm instead of mm
data for F1-01,02: Is the first column necessary? What is Y=2364μm ?
data for F1-01,02,03: Please check units for atomic; atoms/cm^3 instead of %

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

manuscript improved according to all reviewers' comments