Critical Evaluation of Organic Thin-Film Transistor Models
Round 1
Reviewer 1 Report
Review Comments:
In this paper authors have evaluated model of organic thin film transistors. Authors have also analyzed their own proposed model. I found it is interesting to analyze model of TFT. However, there are some concerns related to the practical data of TFTs which they have used to analyze the model. Also, the model they have used to analyze the TFT is a failed model as concluded by authors. So, it doe not solve any problem except analysis. Here are some other concerns which need to be addressed before it gets published:
1. Authors have fabricated DNTT TFTs with channel lengths of 2 um, 8 um, 40 um, and 80 um. The current of these transistors are not consistent specifically considering a 2 um channel length device. This shows that something is wrong in their devices and in this case it may not be interesting to use these devices for analyzing the models.
2. Authors claim that they have analysed models with various TFTs consisting different channel materials and device structures. But I have not seen any I-V curve of other transistors.
3. There are no photos of practical transistors, and there are no physical dimensions of the practical transistors used in the study of the electrical models.
4. Since this is a paper for the study of the electrical models of the TFT transistors. So, it is better in scope of readers related to the semiconductor devices and circuits instead publishing in Crystal Journal.
Above points should be addressed before paper is suitable for the publication in a journal. There are some punctuation mistakes mentioned below otherwise English of the paper is good and acceptable for the publication.
Line 22, be that to design circuits, here it is not clear why to add “be that” in the sentence. “or to further optimize a device,” should be replaced by or further to optimize a device.
Line 70, line 80, full stop should be after references at the end of sentence, apply throughout the whole manuscript
Line 105, “This chapter”. This is not a book so write section instead of chapter. Do not use comma (,) after (i) and similarly other places too.
Author Response
We thank the reviewer for the comments. We are confident that the consideration of these comments further strengthens the argumentation in our manuscript. Below are the detailed answers to the reviewer. This list is provided with the following structure: We first quote the comment (italic). Then we provide our reply and a description of all actions taken that were triggered by the comment. When possible, we highlight these changes in the main text with a yellow background.
"In this paper authors have evaluated model of organic thin film transistors. Authors have also analyzed their own proposed model. I found it is interesting to analyze model of TFT. However, there are some concerns related to the practical data of TFTs which they have used to analyze the model. Also, the model they have used to analyze the TFT is a failed model as concluded by authors. So, it doe not solve any problem except analysis."
RESPONSE: We thank the reviewer for this consistent summary. Indeed, we did not solve the problem of finding a model that correctly describes the TFT. Nevertheless, we solved the problem of reliably testing transistor models, enabling a link between theory and experiment that was not established so far. Such a step is a crucial prerequisite to further develop improved transistor models.
" Here are some other concerns which need to be addressed before it gets published:
1. Authors have fabricated DNTT TFTs with channel lengths of 2 um, 8 um, 40 um, and 80 um. The current of these transistors are not consistent specifically considering a 2 um channel length device. This shows that something is wrong in their devices and in this case it may not be interesting to use these devices for analyzing the models."
RESPONSE: We are not exactly sure what the reviewer means by "something is wrong". We presume, that the evolution of the absolute value of the drain current with channel length may appear inconsistent. The 2µm channel length device has a much smaller channel width compared to the other devices of that series. To avoid such potential confusions, we now add the channel widths to each panel label in Figures 3, 5, and S2.
ACTION TAKEN: We added the channel width of the devices to Figures 3, 5 and S2. Additionally, we generated Table 1 containing information regarding the device architecture and geometry for each set of TFTs (and a reference to it in the text, line 213 to 215).
"2. Authors claim that they have analysed models with various TFTs consisting different channel materials and device structures. But I have not seen any I-V curve of other transistors."
RESPONSE: We appreciate the comment of the reviewer and added I-V curves for each OTFT set.
ACTION TAKEN: We included one exemplary output characteristics for each of the additional sets of TFTs in Figure 6 and a reference to it in the text from line 428 to 433.
"3. There are no photos of practical transistors, and there are no physical dimensions of the practical transistors used in the study of the electrical models."
RESPONSE: We agree. While photos make the manuscript more easily accessible, physical dimensions are crucial to guide readers, in particular TFT experts.
ACTION TAKEN: In Figure 1, we have included a photo of the pentacene TFTs (and a reference to it in the text, line 133 to 138) and in Table 1, we have summarized the analyzed sets of TFTs including their physical dimension (and wrote a reference to it in the text, line 213 to 215).
"4. Since this is a paper for the study of the electrical models of the TFT transistors. So, it is better in scope of readers related to the semiconductor devices and circuits instead publishing in Crystal Journal."
RESPONSE: This manuscript was submitted to the special issue "Thin Film Transistors", which, in our opinion, perfectly fits to our intention to communicate the important insights and analysis methodology from “semiconductor-device physics” to the predominantly materials-oriented community of “Crystal”.
"Above points should be addressed before paper is suitable for the publication in a journal. There are some punctuation mistakes mentioned below otherwise English of the paper is good and acceptable for the publication.
Line 22, be that to design circuits, here it is not clear why to add “be that” in the sentence. “or to further optimize a device,” should be replaced by or further to optimize a device."
RESPONSE: We thank the reviewer for spotting those punctuation mistakes.
ACTION TAKEN: We reformulated the corresponding sentence (Line 24 to 27)
"Line 70, line 80, full stop should be after references at the end of sentence, apply throughout the whole manuscript"
RESPONSE: We thank the reviewer for informing us about this technical mistake.
ACTION TAKEN: All affected citations were changed.
"Line 105, “This chapter”. This is not a book so write section instead of chapter. Do not use comma (,) after (i) and similarly other places too."
RESPONSE: We agree.
ACTION TAKEN: Wording changed in Line 123 and usage of commas revised.
Additional modifications
We meanwhile improved the wording throughout the whole manuscript with minor changes in all paragraphs.
Furthermore, we changed and/or added sentences in following lines:
Line 83 to 87: Reformulation of the hypothesis enabling channel-length-scaling approaches.
Line 316 to 318 and 339 to 340 and throughout the manuscript: Renamed the mobilities µ and µeff to µTLM and µTSFA to make clear that this is the mobility extracted by TLM and TSFA and avoid confusion with the intrinsic channel mobility and the effective mobility used in various publications like [21,31]. In Line 316 to 318, an additional comment on µTLM and µTSFA was added and in Line 339 to 340, a statement distinguishing between effective mobility, intrinsic channel mobility and µTLM, µTSFA was appended.
Reviewer 2 Report
The manuscript is well written and the transistor models are clearly presented and evaluated. I recommend publication after minor revision in the following areas:
Consider adding a table to describe the various TFTs studied and optical images or schematics clearly showing the locations of parameters like Rs, LT, etc.
In line 106 change "cirquit" to "circuit"
Given that fields like displays are the largest applications for TFTs, where the TFT switching characteristics (transfer characteristics) are the key factor, it would be very helpful for display engineers to include transfer characteristics in the model evaluation (IF POSSIBLE).
Author Response
We thank the reviewer for the comments. We are confident that the consideration of these comments further strengthens the argumentation in our manuscript. Below are the detailed answers to the reviewer. This list is provided with the following structure: We first quote the comment (italic). Then we provide our reply and a description of all actions taken that were triggered by the comment. When possible, we highlight these changes in the main text with a yellow background.
"The manuscript is well written and the transistor models are clearly presented and evaluated. I recommend publication after minor revision in the following areas:
Consider adding a table to describe the various TFTs studied and optical images or schematics clearly showing the locations of parameters like Rs, LT, etc."
RESPONSE: We thank the reviewer for these encouraging words. The additional information requested is definitely improving the manuscript.
ACTION TAKEN: We added Table 1 with information about the sets of TFTs (and a reference to it in the text, line 213 to 215). In Figure 1, we included a picture of the set of pentacene TFTs and a schematic drawing of a TFT including an indication of the spatial location of the elements in the equivalent circuit model (and a reference to it in the text, line 133 to 138).
"In line 106 change "cirquit" to "circuit""
RESPONSE: We thank the reviewer for spotting this punctuation mistake.
ACTION TAKEN: We changed it in Line 124 and Line 126
"Given that fields like displays are the largest applications for TFTs, where the TFT switching characteristics (transfer characteristics) are the key factor, it would be very helpful for display engineers to include transfer characteristics in the model evaluation (IF POSSIBLE)."
RESPONSE: We fully agree that transfer characteristics are indeed helpful.
ACTION TAKEN: We added transfer characteristics to Figure 3 and 5.
Additional modifications
We meanwhile improved the wording throughout the whole manuscript with minor changes in all paragraphs.
Furthermore, we changed and/or added sentences in following lines:
Line 83 to 87: Reformulation of the hypothesis enabling channel-length-scaling approaches.
Line 316 to 318 and 339 to 340 and throughout the manuscript: Renamed the mobilities µ and µeff to µTLM and µTSFA to make clear that this is the mobility extracted by TLM and TSFA and avoid confusion with the intrinsic channel mobility and the effective mobility used in various publications like [21,31]. In Line 316 to 318, an additional comment on µTLM and µTSFA was added and in Line 339 to 340, a statement distinguishing between effective mobility, intrinsic channel mobility and µTLM, µTSFA was appended.
Round 2
Reviewer 1 Report
I believe after revision this manuscript is sound to publish. I found a minor mistake in Fig. 6d, where axis is missing drain to source voltage leveIs.
