Because the structure consists of in-plane covalent bonds and inter-layer van der Waals interactions, the electronic properties of monolayer TMDs are highly anisotropic. For example, the conductivity of MoS 2 in the direction parallel to the planar layer (0.1–1 ohm cm) is ~2200 times larger than the conductivity perpendicular to the layers. There are also differences between the properties of a monolayer compared to the bulk material: the Hall mobility at room temperature is drastically lower for monolayer 2H MoS 2 (0.1–10 cm V s) than for bulk MoS 2 (100–500 cm V s). This difference arises primarily due to charge traps between the monolayer and the substrate it is deposited on.