Effect of Annealing Environment on the Performance of Sol–Gel-Processed ZrO₂ RRAM

Round 1

Reviewer 1 Report

In this manuscript, the authors applied sol gel method to prepare the ZrO2 as the insulator in the RRAM. They found that the RRAM device performance after vacuum annealing at 500 degree C exhibited a better performance. However, the ZrO2 based RRAM paper have been published. For example, see S. Lee et al IEEE EDL 39(5) 668 (2018). The authors should point out the difference points, performance or innovation compared with the literature about ZrO2 based RRAM. The discussion or mechanism about the ambient effects was incomplete. There also were a lot of typos in the manuscript.  Figure 5(a) was the endurance properties and Fig.  5(b) was the retention behavior.  The reviewer suggests that this manuscript should be rejected.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The work is interesting and the topic is actual. The manuscript is well written, ordered, clear and concise. The references are adequate, actual and relevant. However, some diffuse analyses impoverish the scientific soundness and support poorly the conclusions. Mainly, each characterization technique deserves a deeper analysis and a more concrete discussion.

For instance, please revise the sentence in lines 77-79: "The FWHM of a GIXRD peak is known to be closely related to the crystallite size, and in a particular, the crystal orientation", and explain how this is related to which planes are first grown. Similarly, please explain the line 86: "the corresponding crystalline sizes for the air annealed and vacuum annealed devices were 10.6 nm and 12.7 nm respectively, with the former exhibiting the greatest size". 10.6 is not larger that 12.7. What do authors mean? By the way, the possibility of preferential growth in these samples should be discussed. Moreover, authors should explain how they obtain thicknesses from the calculated densities (lines 91-92). Contrarily to Scherrer formula, which is very well known, I think Buydens' method deserves a reference.

Also, nor in the Abstract neither in the Conclusions paragraphs is RRAM well defined (lacking the meaning of the first R); and it is not clear what "demonstrated larger crystalline, ..." means (lines 17 and 167). In addition, the sentence in lines 102-105 is quite apart from the rest, makes reference to some XPS spectrum that is not presented, and seems a complete mistake.

Referring to the electrical characterization, please revise the sentence in lines 117-118: "the HRS/LRS current ration was 33 times greater than the RRAM, which consists of ZrO₂ layers annealed in air and N₂." The caption of Fig. 3 makes reference to an inexisting inset showing the image of the RRAM. And it lacks the explanation of what are the spreading in HRS and LRS due to. Also the sentence in lines 154-155 need some revision to make it more clear. A more extensive comparison of the obtained endurance and retention results with the literature could also help to enlighten the contribution of this manuscript to the scientific community.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

In this manuscript, the authors report that the grain size of ZrO2 depended on the ambient at 500 degree C. Could the authors explain the mechanism, what was the materials science for the grain growth of ZrO2 under different ambient?  The resistive memory met a current overshoot issue during electric-forming. A better film quality will suffer a more serious problem than a poor one. This characteristic will lead the device with a damaged insulator, poor in HRS/LRS ratio and endurance reliability. Could the authors comment these film quality issue on the HRS/LRS and endurance in their revised manuscript.    

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

The reviewer has no comment on this manuscript.