Nitrogen surface passivation of the Dirac semimetal Cd3As2

Topological Dirac semimetals, such as Cd${}₃$As${}₂$, possess gapless Dirac nodes in the bulk and topologically protected surface states. In this study, the authors show that the magnetotransport properties of epitaxial thin films of Cd${}₃$As${}₂$ depend sensitively on the nature of the exposed film surface. For example, it is shown that nitrogen plasma passivation allows for observation of the quantum Hall effect from the surface states. The results highlight the importance of band bending and surface chemistry in the relative contributions from surface and bulk states to the measured transport properties.