  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.
