Manipulating the Topological Surface States of Cd₃As₂by N* Plasma Exposure

Cd₃As₂belongs to the family of three-dimensional Dirac semimetals, which are characterized by a linear dispersion of their bulk bands at the Fermi energy. For thin films, the electronic transport properties of Cd₃As₂are dominated by surface states, which, as we show in this presentation, are highly sensitive to the chemistry of the surface. Temperature-dependent magneto-transport measurements show that exposure of the surface to a low-energy nitrogen plasma improves carrier mobility and facilitates the observation of the quantum Hall effect in confined thin films. X-ray photoemission spectroscopy reveals changes in the surface chemistry of air-exposed and nitrogen-plasma surfaces, respectively. The results provide insights into the role of surface band bending and the relative contributions of surface and bulk states to the measured transport properties.