High Performance of Nanostructured Cu2O-Based Photodetectors Grown on a Ti/Mo Metallic Substrate
, June Key Lee 3, Meera Moydeen Abdul Hameed 4, Badr M. Thamer 4, Abdullah M. Al-Enizi 4, Rayana Ibrahim Alkhalifah 4 and Wael Z. Tawfik 1,*Round 1
Reviewer 1 Report
In this work, RF sputtered films of Cu2O deposited on Mo-glass substrate (as an alternative to classical FTO) were investigated as photodetector candidate material. A comprehensive investigation by XRD, FE-SEM, and XPS of the films was included also as part of the study.
There are a few issues that need to be addressed with the current version of the manuscript:
Line 14: through (not "throughout")
Line 15: define acronym FTO at the time of its first occurrence here
Line 16: replace "it appeared" with "proved"
Line 30: cross out the word "response"; the electrical signal is the response
Line 35: cross out "that are produced by photons" as this is repetitive with the previous part of the phrase
Line 37: photodetector applications (without the "s" in "photodetectors")
Line 39: please revise! It does not sound logical at all.
Line 42: and are utilized ("and" is necessary here to connect the two predicates of the phrase "include" and "are utilized")
Line 45: cross out "where" as it does not belong here
Line 47: What do you mean by "potential" characteristics? What potential characteristics?
Lines 52-53: What did you mean to say by "it is chemically in electrolytic solutions"? It does not make sense.
Line 58: explain the acronym RF, although quite well known
Line 58: add copula "are" before "characterized"
Line 62: chemical (not "chemichal")
Line 71: Please revise! It does not sound right at all.
Line 105: IR light (cross out the word "spectral" as it is superfluous)
Line 109: "Planck" should be capitalized as it is the name of a great scientist
Line 152: film surface (not "film's" because it is an object, not a person)
Line 179: leading "to" (not "for")
Line 183: Responsivity (second "i" is missing)
Lines 184 and again 220: "All of these for .... electrode" - This sentence sounds very unprofessional. Please revise your figure captions!
Line 186: photodetector responsivity (not "photodetector's")
Table 1, third column: Jones ("s" missing)
Line 303: substrate ("e" missing)
Line 307: What does "sccm" mean? Explain or use proper SI units!
Materials and Methods: probably the weakest section of the entire manuscript.
3.1. You need to describe vendor and purity for all raw chemicals used in the experiments (Ti, Mo-glass, FTO, Cu2O, etc.)
3.2. Way too brief. Need to provide more operation details for FE-SEM and XPS (settings used, sources, stages, parameters, etc.)
Line 333: layers (plural), because a plural verb follows
Conclusions are rather a summary of the work, then true conclusions with importance of findings and future perspectives. Also, all verbs in the Conclusions should be past tense, because they describe results already obtained and presented in the manuscript by the time the conclusions come in.
English is quite weak. Extensive English editing at the time of revision is required.
Author Response
Response to Reviewer #1
In this work, RF sputtered films of Cu2O deposited on Mo-glass substrate (as an alternative to classical FTO) were investigated as photodetector candidate material. A comprehensive investigation by XRD, FE-SEM, and XPS of the films was included also as part of the study.
There are a few issues that need to be addressed with the current version of the manuscript:
Response: Thank you for comments and valuable notes. Now we have corrected all comments.
Line 14: through (not "throughout") =< We have corrected it.
Line 15: define acronym FTO at the time of its first occurrence here =< OK
Line 16: replace "it appeared" with "proved" =< Done
Line 30: cross out the word "response"; the electrical signal is the response =< OK
Line 35: cross out "that are produced by photons" as this is repetitive with the previous part of the phrase =< OK
Line 37: photodetector applications (without the "s" in "photodetectors") =<We have corrected it.
Line 39: please revise! It does not sound logical at all. =< We now have revised it.
Line 42: and are utilized ("and" is necessary here to connect the two predicates of the phrase "include" and "are utilized") =< OK
Line 45: cross out "where" as it does not belong here =< OK
Line 47: What do you mean by "potential" characteristics? What potential characteristics? =< potential means numerous. We have corrected it.
Lines 52-53: What did you mean to say by "it is chemically in electrolytic solutions"? It does not make sense. =< We now have corrected it to be “it has high chemical stability in electrolytic solutions”.
Line 58: explain the acronym RF, although quite well known =< OK
Line 58: add copula "are" before "characterized" =< OK
Line 62: chemical (not "chemichal") =< We have corrected it.
Line 71: Please revise! It does not sound right at all. We have revised it.
Line 105: IR light (cross out the word "spectral" as it is superfluous) =< OK
Line 109: "Planck" should be capitalized as it is the name of a great scientist =< We have corrected it.
Line 152: film surface (not "film's" because it is an object, not a person) =< We have corrected it.
Line 179: leading "to" (not "for") =< We have corrected it.
Line 183: Responsivity (second "i" is missing) =< We have corrected it.
Lines 184 and again 220: "All of these for .... electrode" - This sentence sounds very unprofessional. Please revise your figure captions! We have now revised it.
Line 186: photodetector responsivity (not "photodetector's") =< We have corrected it.
Table 1, third column: Jones ("s" missing) =< We have corrected it.
Line 303: substrate ("e" missing) =< We have corrected it.
Line 307: What does "sccm" mean? Explain or use proper SI units! =< sccm is standard cubic centimeters. We have now explained it.
Materials and Methods: probably the weakest section of the entire manuscript. =< We have improved this section to be clearer.
3.1. You need to describe vendor and purity for all raw chemicals used in the experiments (Ti, Mo-glass, FTO, Cu2O, etc.) =< We have now described vendor and purity for all raw chemicals used in the experiments
3.2. Way too brief. Need to provide more operation details for FE-SEM and XPS (settings used, sources, stages, parameters, etc.) =< We have now added the operation details for FE-SEM and XPS.
Line 333: layers (plural), because a plural verb follows =< OK
Conclusions are rather a summary of the work, then true conclusions with importance of findings and future perspectives. Also, all verbs in the Conclusions should be past tense, because they describe results already obtained and presented in the manuscript by the time the conclusions come in. =< We have improved this section to be clearer.
The manuscript has been resubmitted to your journal. We look forward to your positive response.
Sincerely,
<Prof. Wael Z. Tawfik>
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript describes the synthesis and characterization of Cu2O thin films supported on different substrates, including the optoelectronic response of the materials for their potential use as photodetectors.
From the title I expected a sound optoelectronic characterization of the materials to explain the "facile charge transfer" of the materials tested, nevertheless, no solid evidence was presented to tackle this issue. Moreover, the presentation and discussion of results does not bring significant insights to the field to recommend it for publication. The authors present a technical report where different techniques were employed to characterize the obtained materials but do not discuss the reasons behind the different observed trends.
In summary, I encourage the authors to conduct a systematic analysis of the results and use relevant techniques (such as transient absorption) to unravel the mechanisms behind the behavior of the samples.
Additionally
- Figure 8 is very confusing, what is the role of Ag? This is not mentioned in the text
- Can the authors explain the reason behind the more than 100 % EQE
- Types of heterojunctions need to be mentioned
- Time-resolved measurements will be valuable
- Title is misleading
Several typos and grammar mistakes were spotted in the manuscript, this hinders the reading and understanding of the ideas behind the manuscript.
Author Response
Response to Reviewer #2
The manuscript describes the synthesis and characterization of Cu2O thin films supported on different substrates, including the optoelectronic response of the materials for their potential use as photodetectors.
From the title I expected a sound optoelectronic characterization of the materials to explain the "facile charge transfer" of the materials tested, nevertheless, no solid evidence was presented to tackle this issue. Moreover, the presentation and discussion of results does not bring significant insights to the field to recommend it for publication. The authors present a technical report where different techniques were employed to characterize the obtained materials but do not discuss the reasons behind the different observed trends.
Response: We would like to start by thanking you for reading our manuscript and guiding us through your valuable comments. Thank you very much for sharing your helpful comments.
In summary, I encourage the authors to conduct a systematic analysis of the results and use relevant techniques (such as transient absorption) to unravel the mechanisms behind the behavior of the samples.
Response: We agree with the reviewer’s comment. However, we don’t have such these useful techniques. Instead, we have computed all parameters including external quantum efficiency, sensitivity, responsivity, and detectivity based on our experimental data in order to clarify the required meaning of the "facile charge transfer".
Additionally
- Figure 8 is very confusing, what is the role of Ag? This is not mentioned in the text
Response: We have redrawn this figure to be clearer and we have explained the role of Ag in the text.
- Can the authors explain the reason behind the more than 100 % EQE.
Response: The EQE = number of charge carriers collected by the detector to the number of photons of a given energy. Thus, the EQE may be over 100% if you can generate two pairs of carriers in one photon.
- Types of heterojunctions need to be mentioned
Response: We have now mentioned it.
- Time-resolved measurements will be valuable
Response: We agree with the reviewer’s comment. However, we don’t have such these useful techniques. Instead, we have computed all parameters including external quantum efficiency, sensitivity, responsivity, and detectivity based on our experimental data in order to clarify the required meaning of the "facile charge transfer".
- Title is misleading
Response: We thank the reviewer’s comment. The main aim of this work is clarification for the reader that the usage of a Ti-metal as a substrate for the growth of semiconductors can offer a conductive path for the charge carriers produced by incident photons, which in turn improves the effectiveness of carrier extraction "transfer". Thus, the current title is most appropriate to describe the article.
The manuscript has been resubmitted to your journal. We look forward to your positive response.
Sincerely,
<Prof. Wael Z. Tawfik>
Author Response File: Author Response.docx
Reviewer 3 Report
The manuscript entitled " Facile charge transfer of nanostructured Cu2O based photodetectors grown on a Ti/Mo metallic substrate " prepared a Cu2O detector for visible light from 410nm to 636nm and the results are promising compared to previous works. The consist of the device layer and working mechanism is well studied so this article can be considered for publication after the following problem has been resolved.
1. The manufacturing process is introduced rather vague. The choice of pre-set parameters must be chosen for a reason.
2. There is no chart showing the device’s ideal geometry.
3. There is no further analysis of the sputtering growth of cuprous oxide. For example, why the FTO substrate doesn’t support RF sputtering well?
4. It is important to highlight the applicability of the results to further work by including prospects for future research in conclusion.
No
Author Response
Response to Reviewer #3
The manuscript entitled "Facile charge transfer of nanostructured Cu2O based photodetectors grown on a Ti/Mo metallic substrate" prepared a Cu2O detector for visible light from 410nm to 636nm and the results are promising compared to previous works. The consist of the device layer and working mechanism is well studied so this article can be considered for publication after the following problem has been resolved.
Response: We would like to start by thanking you for reading our manuscript and guiding us through your valuable comments. Thank you very much for sharing your helpful comments.
- The manufacturing process is introduced rather vague. The choice of pre-set parameters must be chosen for a reason.
Response: For more clarity, we have now described vendor and purity for all raw chemicals used in the experiments and we have added the operation details for all used equipment in Materials and Methods part.
- There is no chart showing the device’s ideal geometry.
Response: We have now added a chart to show the device’s ideal geometry as a Fig. 8b.
- There is no further analysis of the sputtering growth of cuprous oxide. For example, why the FTO substrate doesn’t support RF sputtering well?
Response: We thank the reviewer’s comment. The morphological structure analysis for Cu2O grown on traditional FTO and on Ti-metallic substrate was explained this issue in detail.
“As in Fig. 4(a), Cu2O grown on the traditional FTO substrate initially looked as scattered fragmented particles, it can be described as having a granular structure. Additionally, the existence of observable pinholes on the Cu2O film surface suggests that the FTO substrate does not support sputtering well, which may has an impact on the optical properties and the performance of the deposited film. On the other hand, as depicted in Fig. 4(b) it is clear that the Cu2O coated on the Ti-metallic wafer appears to be tightly packed and entirely covers the surface of the Ti-Mo substrate. The enhancement of the morphological properties in case of Cu2O layer grown on Ti-Mo substrate could be primarily assigned to better Ohmic contact in addition to the higher electrical conductivity of the metallic substrate, which encouraged the growth of sputtered Cu2O film on its surface. Conversely, the usage of traditional FTO with a lower conductivity leads to suppress the surface passivation with Cu2O layer.
- It is important to highlight the applicability of the results to further work by including prospects for future research in conclusion.
Response: We agree with the reviewer’s comment. Therefore, we have improved this section to highlight the applicability of the results to further work by including prospects for future research.
The manuscript has been resubmitted to your journal. We look forward to your positive response.
Sincerely,
<Prof. Wael Z. Tawfik>
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The title of the manuscript is still misleading, the authors have replied to my comments by providing theoretical information about important phenomena such as charge transfer, so I highly encourage the authors to include the word "theoretical" or "theoretical study" in the title to avoid confusions.
Moderate editing required
Author Response
Response to Reviewer #2
The title of the manuscript is still misleading, the authors have replied to my comments by providing theoretical information about important phenomena such as charge transfer, so I highly encourage the authors to include the word "theoretical" or "theoretical study" in the title to avoid confusions.
Response: We have modified it to appropriate title “High performance of nanostructured Cu2O-based photodetectors grown on a Ti/Mo metallic substrate”.
The manuscript has been resubmitted to your journal. We look forward to your positive response.
Sincerely,
<Prof. Wael Z. Tawfik>
Author Response File: 
Author Response.pdf
