Nanoscale triboelectrification gated transistor

Tribotronics has attracted great attention owing to the demonstrated triboelectrification-controlled electronics and established direct modulation mechanism by external mechanical stimuli. Here, a nanoscale triboelectrification-gated transistor has been studied with contact-mode atomic force microscopy and scanning Kevin probe microscopy. The detailed working principle was analyzed at first, in which the nanoscale triboelectrification can tune the carrier transport in the transistor. Then with the manipulated nanoscale triboelectrification, the effects of contact force, scan speed, contact cycles, contact region and charge diffusion on the transistor were investigated, respectively. Moreover, the manipulated nanoscale triboelectrification serving as a rewritable floating gate has demonstrated different modulation effects by an applied tip voltage. This work has realized the nanoscale triboelectric modulation on electronics, which could provide a deep understanding for the theoretical mechanism of tribotronics and may have great applications in nanoscale transistor, micro/nano-electronic circuit and nano-electromechanical system.

The manuscript is well prepared and well written. However, I have some minor comments and questions. The manuscript can be accepted after addressing the following comments: 1) It seems like the KPFM contrast saturates very fast as a function of contact force and scan number. Can the authors comment on this. Adding couple of sentences for clarification will help general readership. 2) Have the authors tried experiments with force lower than 1 nN to see the response trend?
3) It is also great idea to investigate scan speed. Have the authors conducted scan speeddependent trend? If so, please add some comments for clarity. 4) From the application perspective, is there any optimal surface oxide value for the nanoscale triboelectrification-gated transistor? 5) Recently there have been reports about electron tunneling in tribo contacts when the thickness is extremely small (Liu, et al. Nature nanotechnology 13, 112 (2018); Nano Energy 48, 320 (2018); Matter 1, 650 (2019). Is it possible to exploit tunneling concept in this arrangement. This may allow operation with extremely small currents thus increasing the energy efficiency in electronics (lower heat).

Reviewer #2 (Remarks to the Author):
The authors demonstrated triboelectrification-controlled electronics and established direct modulation mechanism by external mechanical stimuli. They studied a nanoscale triboelectrification-gated transistor (NTT) with contact-mode atomic force microscopy (AFM) and scanning Kevin probe microscopy. However, the concept of triboelectrification-gated transistor (NTT) has been introduced by the coupling of contact electrification and electrostatic induction (ref. Wenbo Peng et al., ACS Nano2016. 10, 4, 4395-4402) As well as, the study of manipulated nanoscale triboelectrification by AFM including the effects of contact cycles, contact region and charge diffusion on the characteristics of the dielectric surface has been well known (ref. Yu Sheng Zhou et al., Nano Lett.2013.13, 6, 2771-2776). This paper was well organized but has no novelty. Therfore, I am afraid I am not persuaded that these findings represent a sufficiently striking conceptual advance to justify publication in Nature Communications. For these reasons, I feel that these findings would be better suited for publication in an alternative journal. It is necessary to prove that the gating effect by triboelectrification is sufficient to operate the p-Si channel. The author should check the following.
-All Id-Vd curves were not saturated. The author should check the data in the range of Vd over 5V.
-The bottom gate structure of Figure 2, p-Si / oxide gate insulator / p-Si structure, is not suitable for comparison with the concept of triboelectrification-gated transistor (NTT). The device performance according to gate bias should be compared with the top metal gate electrode based on the same structure of Figure 5a. It is necessary to prove whether the role of the actual metal gate electrode can be replaced with triboelectrification-gating by checking the performance, mobility, Ion/off ratio, and Vth etc. -In the inset of Figure 5e, it is necessary to show that Id is saturated by increasing the tip voltage, especially the negative direction. mechanical stimuli [29][30][31][32] Rev 2. Page 3, line 3-6: However, the interactive interfaces between external environment and electronics in current tribotronic devices are all in the macro scale, which has limited the integration and modularization of tribotronics. When the size scales down to the micro or nano range, whether the modulation effect still exists is a critical question for tribotronics.   Figure S4, as the contact force increases in the low range, more charges are transferred that leads to the rise of the highest filled surface energy state of SiO 2 . When the contact force increases to 2 nN, the amount of transferred charges is large enough to make the highest filled surface energy state of SiO 2 almost as high as the Fermi level of Si. So, the contact force larger than 2 nN will hardly lead to more transferred charges, and the KPFM contrast shows the fast saturation. According to Figure 2, when the SiO 2 surface is scanned twice by the AFM Si tip, the amount of transferred charges is large enough to make the highest filled surface energy state of SiO 2 almost as high as the Fermi level of Si. So, the increasing contact cycles (more than 2) will hardly lead to more transferred charges, and the KPFM contrast shows the fast saturation.

Reviewer #1
This is an excellent manuscript dealing with very novel application of triboelectricity. The manuscript is well prepared and well written. However, I have some minor comments and questions. The manuscript can be accepted after addressing the following comments: Response: Thank you very much for your positive comments on the manuscript. We will make persistent efforts.  [1] . In this process, the increasing contact force can decrease the potential barrier and induce more electrons to transfer onto the SiO 2 surface, until reaching the saturation state when the highest filled surface energy state of SiO 2 is as high as the Fermi level of Si [2] . In the revised Figure   S4, as the contact force increases in the low range, more charges are transferred that leads to the rise of the highest filled surface energy state of SiO 2 . When the contact force increases to 2 nN, the amount of transferred charges is large enough to make the highest filled surface energy state of SiO 2 almost as high as the Fermi level of Si. So, the contact force larger than 2 nN will hardly lead to more transferred charges, and the KPFM contrast shows the fast saturation.
Similarly, the increasing scan number can also induce more transferred charges and leads to the rise of the highest filled surface energy state of SiO 2 . According to  could not decrease to a too small value considering the tunneling effect. This could provide a general design guidance of the surface oxide value for the device fabrication.
We will also detailedly analyze the effect of surface oxide value in our future work.  Response: Thank you very much for the suggestion. We have fabricated a top metal gate electrode on the transistor ( Figure S9a). The corresponding I d -V tg transfer curve is shown in Figure S9b, from which we can calculate the mobility ( =