Abstract Negative Differential Conductance (NDC) is a hallmark anomalous phenomenon in transport measurements, which is relatively rare in scanning tunneling microscopy due to its direct association with the local density of states. In this work, we constructed an ultrathin two-dimensional metal/semiconductor heterostructure by epitaxially growing a bilayer bismuth (Bi) film on a tin selenide (SnSe) substrate, revealing a unique moiré pattern arising from lattice mismatch. Spatially resolved tunneling spectroscopy detected a prominent NDC feature at approximately −650 meV. Both the energy position and depth of the NDC dip are strictly modulated by the periodicity of the moiré pattern. Our work not only establishes a novel Bi/SnSe material platform exhibiting NDC but also reports the visualization of NDC spatially modulated by a two-dimensional moiré superlattice, providing insight for the moiré electronics.
Sun et al. (Tue,) studied this question.