A CMOS-Compatible Silicon Nanowire Array Natural Light Photodetector with On-Chip Temperature Compensation Using a PSO-BP Neural Network

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper entitled “A CMOS-Compatible Silicon Nanowire Array Natural Light Photodetector with On-Chip Temperature Compensation Using a PSO-BP Neural Network”. The concept of monolithic optical and thermal sensing combined with AI compensation is interesting and potentially useful. However, there are some serious issues with quantitative performance that must be addressed before the manuscript can be accepted.

 

1. Please provide numerical error metrics before and after compensation
2. Network architecture is not stated. What is exact number of hidden neurons? Provide a link to github with implementation.
3. You write “Silicon nanowire (SiNW) photodetectors exhibit exceptional sensitivity” - exceptional compared to what? Add a paragraph about it to the introduction.
4. A similar concept of using the thermal radiation for precise temperature measurement has been demonstrated in spectral pyrometry systems that operate without prior knowledge of surface emissivity [10.1134/S0020441214010072] add this to introduction to present the work for a broader context.
5. What is the sensitivity of the SiNW temperature sensor? Number(V/C)?

6.What is the compensation accuracy.

 

 

7. English is good. I found only one minor issue:

line 357 an gold-coated SiNW

 

Author Response

We appreciate the two reviewers’ meticulous reading and valuable suggestions on our manuscript. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. We have sent the revised paper and point-to-point response as attachments for the reviewers to review.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper employs a dual-array architecture consisting of a photosensitive silicon nanowire array and a thermally sensitive gold-coated silicon nanowire array. This design enables the simultaneous acquisition of optical and temperature signals. By utilizing a hybrid temperature compensation algorithm, the issue of performance degradation due to thermal drift is effectively mitigated, thereby enhancing the stability and reliability of the photodetector across a wide temperature range. This research provides a feasible strategy for developing highly stable and integrated optical sensing systems. However, there are still some aspects regarding the device fabrication details and performance characterization methods that require clarification and refinement. The reviewer recommends that this paper could be accepted with Major revisions for publication in Micromachines.

Following are some Major issues:

1. Regarding the characterization of the photoelectric properties of the silicon nanowire array, clarification is needed on the following points: (1) Does the reported photocurrent represent the summation of signals from all individual devices? (2) Was the optical power measured using a laser or natural light? Please provide the relevant experimental details. Additionally, the methodology for extracting the response time from the I-t curve appears to be problematic. It is recommended to retest the response time following established standards for accuracy.
2. Page 6, lines 192-197, the authors discuss the working mechanism, stating that “The sensing mechanism is based on the photoconductive effect…” I am confused by these descriptions. I have two questions here. First, the band structure is confusing. Why do the authors think that after absorbing light, conduction band electrons will transition to donor levels? Is there any evidence in this paper to support this? If not, I suggest that the authors avoid this presentation method, as it can easily lead to ambiguity. I believe that the boron doping in this paper is intended to achieve P-type doping of Si nanowires, and the photoresponse should primarily come from intrinsic light absorption. Second, related to the previous question, in nanowires, localized states caused by surface states or disordered structures may affect the photoelectric properties of the channel by trapping free carriers. These additional energy levels introduced by localized states can trap and store carriers. In this case, the process of valence band electrons transitioning to these localized energy levels requires further explanation. The authors can refer to “Slowing Hot-Electron Relaxation in Mix-Phase Nanowires for Hot-Carrier Photovoltaics” published in Nano Letters.
3. Typically, nanowires are often perpendicular to the surface, making it easier to achieve resonant absorption effects to enhance light absorption and simpler to deposit electrode materials. This is very common in many previous works, whether using top-down or bottom-up methods to fabricate nanowire array devices. For example, “Tapered InP nanowire arrays for efficient broadband high-speed single-photon detection” published in Nature Nanotechnology. Why did this paper choose an inclined structure?
4. Figure 6d presents the results after applying temperature compensation. Through data fusion processing, the thermal effect is effectively suppressed, enabling high-precision readings of optical power density. What is the specific meaning of the second row of voltage values in Figure 6d?
5. In the Materials and Methods section, it is mentioned that a dually-passivated sloped thin-wall structure is formed via etching. While Figure 1 includes many schematic diagrams, a characterized cross-sectional view of the actual device is absent. Although the paper states that the nanowire arrays, fabricated using CMOS-compatible processes, exhibit excellent uniformity, the electron microscopy image in Figure 1f suggests that the uniformity of the thermal sensing array (lower section) still requires attention. Additionally, how are the sputtered metal electrodes connected to the silicon nanowire arrays? And please provide the specific size (e.g., diameter, length) of the nanowires.
6. The English expression in this manuscript requires improvement, and it is strongly recommended that the authors optimize it in the revised version.

 

Author Response

We appreciate the two reviewers’ meticulous reading and valuable suggestions on our manuscript. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. We have sent the revised paper and point-to-point response as attachments for the reviewers to review.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

good job with this revision! accept in current form

 

proofread for typos:

e.g.

spectrapyrometry(line 89)

Reviewer 2 Report

Comments and Suggestions for Authors

I think this work can be accepted in the current form