The development of commercially available flexible and wearable devices requires low‐operating‐voltage circuit and resistive random access memory (RRAM). This paper reports the preparation and performances of low‐operating‐voltage RRAM based on the interlayer‐spacing regulation of MoSe2. Twine‐jumble‐like MoSe2 clusters were synthesized via hydrothermal method. The average interlayer spacing in the clusters is higher than the value for bulk MoSe2 by 9.969%. The layer count of the MoSe2 sample predicted according to the experimental value of in the Raman spectroscopy is 1.403 while it is 2 regarding the characteristic of A1g peak and the existence of B2g peak, which is inconsistent with the results of scanning electron microscope and transmission electron microscope. Calculation of van der Waals force reveals that the twine‐jumble‐like MoSe2 should not be considered as a bi‐layer (or few‐layer) crystal, but as a cluster consisting of a numerous monolayer crystals. Compared with the conventional nanosized MoSe2, the SET/RESET voltages of the RRAM device based on the monolayer MoSe2 clusters are decreased by 4–10 times while the switching ratio and endurance are increased by 2–40 and 2–10 times respectively, which is due to that the interstitial radius in the monolayer MoSe2 clusters is higher than that of a silver ion.

Low power and high switching ratio are the development direction of the next generation of resistive random access memory (RRAM). Previous techniques could not increase the switching ratio while reducing the SET power.Here, we report a method to fabricate low-power and highswitching-ratio RRAM by adjusting the interstice radius (r g ) between the van der Waals (vdW) layers of transitional-metal dichalcogenides (TMDs), which simultaneously increases the switching ratio and reduces the SET power. The SET voltage, SET power, switching ratio and endurance of the device are strongly correlated with r g . When the ratio of r g to the radius of the metal ions that form the conductive filaments (r g /r Ag + ) is near 1, the SET voltage and SET power vertically decrease while the switching ratio vertically rises with increasing r g /r Ag + . For the fabricated Ag/[SnS 2 /poly(methyl methacrylate)]/Cu RRAM with an r g /r Ag + of 1.04, the SET voltage, SET power and switching ratio are 0.14 V, 10 −10 W and 10 6 , respectively. After 10 4 switching cycles and a 10 4 s retention time, the switching ratio of the device can still be stable above 10 6 . Bending has no influence on the performance of the device when the bending radius is not <2 mm.

Single-layer molybdenum disulfide (MoS2) has attracted a significant amount of interest owing to its excellent electrical, optical, and mechanical properties. In this paper, we study that the effects of the distance between the molybdenum source and substrate as well as the substrate angle on the morphology, size, and structure of MoS2 films grown from molybdenum trioxide (MoO3) sulfide on sapphire substrates via the Chemical Vapor Deposition (CVD) by using Scanning electron microscopy (SEM), Raman spectra and Photoluminescence spectra (PL). On the results show that the distance between the substrate and molybdenum source affects the controllable growth of MoS2 films. When the substrate is too close to the molybdenum source, it results in increasing amount of non-reduced MoO3 particles which were deposited on the substrate. When the distance between the substrate and molybdenum source is too large, only a small amount of MoS2 is deposited on the substrate. High-quality MoS2 films can be prepared when the molybdenum source and substrate are 9.5 cm apart. When the substrate is inclined 30° and placed downstream of the molybdenum source with a distance of 9.5 cm, the size of the prepared single-layer MoS2 is approximately 100 μm, which is greater than that of MoS2 prepared on the horizontal face-up substrate.

The CVD-grown 2D MoS2 is the oxygen-doped MoS2. Annealing treatment can increase the O-doping concentration in the CVD-grown 2D MoS2 while vulcanization can make the CVD-grown 2D MoS2 transition from the an oxygen-doped state to the a pure state.