Abstract
Standard semiconductor fabrication techniques are used to fabricate a quantum dot (QD) made of WS2, where Coulomb oscillations were found. The full-width-at-half-maximum of the Coulomb peaks increases linearly with temperature while the height of the peaks remains almost independent of temperature, which is consistent with standard semiconductor QD theory. Unlike graphene etched QDs, where Coulomb peaks belonging to the same QD can have different temperature dependences, these results indicate the absence of the disordered confining potential. This difference in the potential-forming mechanism between graphene etched QDs and WS2 QDs may be the reason for the larger potential fluctuation found in graphene QDs.
Highlights
After demonstrating a variety of electronic applications on graphene[1], graphene-like two-dimensional layered materials have attracted the increasing attention of researchers because of their unique properties[2,3]
The anomalous behavior of Coulomb peaks in a graphene etched quantum dot (QD) is widely considered to be the result of a disordered confining potential[32] since the edge states are formed in the narrow constrictions connecting the QD and the reservoirs. This disordered confining potential may limit the performance of the graphene etched QD because low-frequency noise experiments on graphene QDs exhibit a larger fluctuation of potential[21]
The difference, which relates to the edge states, in the barrier-forming mechanisms of an graphene etched QD and a WS2 QD, may contribute to the larger noise level found in graphene QDs
Summary
After demonstrating a variety of electronic applications on graphene[1], graphene-like two-dimensional layered materials have attracted the increasing attention of researchers because of their unique properties[2,3]. Transition metal dichalcogenides (TMDCs) are considered one of the most promising two-dimensional post-graphene materials for electronics owing to the presence of a band gap ranging from 1 to 2 eV6,7. Unlike etched quantum dots (QDs) made on semimetallic graphene[18,19], semiconducting TMDCs have a band gap large enough to form a QD using the electric field. This QD decreases the influence of the edge states, which are a major aspect limiting the performance of graphene nano-devices[20,21]. The temperature dependence of the Coulomb peaks is www.nature.com/scientificreports/
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