STM spectroscopy measurements of R-type and H-type twisted MoSe₂/WSe₂ heterostructures

When semiconducting transition metal dichalcogenides heterostructures are stacked, the twist angle and lattice mismatch leads to a periodic moiré potential. As the angle between the layers changes, so do the electronic properties. As the angle approaches 0- or 60-degrees, interesting characteristics and properties occur. Here we report low temperature scanning tunneling microscopy and spectroscopy measurements on the band gaps and band modulations in MoSe₂/WSe₂ heterostructures with near 0 degree rotation (R-type) and near 60 degree rotation (H-type). We show that the modulation of the band edge for the R-type is isolated to the valence band while the modulation for H-type occurs at both the conduction and valence band edges. The modulation in the bands and the band gaps for the R-type are overall larger than that of the H-type. Local density of states images reveal that electrons are localized differently at the valence band and conduction band edges of the H-type device.