Growth and Electronic Properties of (Zn_xCd_1-x)₃As₂ Thin Films

The three-dimensional Dirac semimetal Cd₃As₂ has been utilized as a prototypical system for studying the physics of Dirac states and the interesting transport and optical properties they support. Additionally, the ability to epitaxially grow thin films on zinc blende semiconductors has opened the door to utilizing Cd₃As₂ in devices. Successfully exploiting the distinct properties of Cd₃As₂ for technological applications will require advanced understanding of their dependence on disorder, doping, and defects. The ability to further tune its electronic properties will offer pathways for ultimately designing this material for next-generation technologies.

Here, the addition of Zn is explored as a method to alter electronic properties as well change the crystal structure in thin films grow by molecular beam epitaxy. Large percentages of Zn substitution on the Cd sublattice (>25%) are found to shift the as-grown Cd₃As₂ epilayers from n-type to p-type, while small percentages lower the carrier concentration preserve the high mobility of electrons. Zn alloying is further found to result in smoother surfaces, and X-ray diffraction and Raman reveal that it additionally alters the structure and symmetry of the thin films. In particular, Raman modes are broadened, and polarization dependence is reduced with increasing Zn content.