Review Reports

Round 1

Reviewer 1 Report

coatings-1039845

The manuscript „ Improving transport properties of GaN-based HEMT on Si (111) by controlling SiH4 flow rate of the SiNx nano-mask" by Jin-Ji Dai et al. contains set of interesting information on the preparation and performance characteristics of epitaxially grown GaN layers. The text is well written, introductory part contains concise review of most of the latest works dedicated to the topic with clear indications to the experimental work, although the novelty off the presented research is not precisely stated. The paper is worth to publish in Coatings after additional revision. All the figures are legible and correctly described, but their discussion should be deepened based on literature data on similar systems. Moreover, the results of calculations presented in the table 1 and in graph 5 do not contain information on standard deviations (error bars). How many repetitions for each growth was performed to get the data presented in the paper? Please include the diffractograms based on which the data in table 1 were calculated. The conclusions are presented too briefly, they should be expanded to highlight the most important elements of the novelty of the performed experimental work in context of the progress made in the field.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

In the paper “Improving transport properties of GaN-based HEMT on Si (111) by controlling SiH4 flow rate of the SiNxnano-mask” the authors report the fabrication of AlGaN/AlN/GaN high electron mobility transistor structures grown on Si (111) substrate by metalorganic chemical vapor deposition in combination with the technique of SiNx nano-mask inserted into the low-temperature GaN buffer layer. They investigate the impact of SiH4 flow rate on two-dimensional electron gas properties, finding that controlling the SiH4 flow rate of the SiNx nano-mask grown at low temperatures in a short time is an effective strategy to overcome surface desorption. Finally, they analyze the electrical transport properties of the devices reporting that the highest mobility and carrier concentration of the sample can be achieved under an optimized SiH4 flow rate of 50 sccm.

Overall, the paper presents interesting results, well supported by experimental data. For this reason, I recommend publication after the authors have clarified some minor points listed below:

1) The authors claim that, below a SiH4 flow rate of 50 sccm, the mobility enhances with increasing the SiH4 flow rate. They attribute this effect to the reduction of dangling bonds that could generate acceptor-like trap levels in the band structure, capturing free charges and then forming negatively charged Coulombic scattering centers. The interaction between the carriers and the scattering centers is strongly influenced by the temperature (see for instance https://doi.org/10.1021/acsami.0c00348). I wonder if the authors have performed any electrical characterization as a function of temperature.

2) The authors also claim that below a SiH4 flow rate of 50 sccm, the increase of carrier concentration with decreasing edge-type TDs is a result of charge de-trapping from the acceptor-like traps. I do not see how there can be a detrapping since, as the authors also state, the formation of trap states is suppressed at this flow rate. This explanation seems to contradict the one given for the increase in mobility. Please clarify this point.

3) Please read the article carefully and correct all grammatical errors and rephrase sentences that are unclear.

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf