(001) Grown by Molecular Beam Epitaxy

Cadmium arsenide (Cd₃As₂) is a 3D Dirac semimetal in which two Dirac nodes along the k_z axis are stabilized by a symmetry of the crystal lattice. In a thin film, the fate of the Dirac nodes and associated surface states depends on the orientation of the confinement potential, which is effected by the growth direction. Here we report on improvements to the epitaxial growth of (001)-oriented cadmium arsenide thin films on a III–V compound semiconductor substrate. We show that smooth films can be achieved by altering the surface chemistry at the epilayer–buffer layer interface. We discuss the nature of the resulting clean, two-dimensional transport on the (001)-like surfaces with reference to previous work on the more widely studied (112)-like surfaces.