Controlling defect formation and transport properties in Cd₃As₂ through epitaxial growth

Three-dimensional topological semimetals have been demonstrated to host extraordinary properties such as high mobilities and magnetoresistances. The Dirac semimetal Cd₃As₂ in particular has been the focus of intense study and has been synthesized in thin film form. This is an essential step towards implementing it in next generation electronic devices. However, it is crucial to now understand the predominant types of defects induced by film growth and their role in the magneto-transport properties. This includes both minimizing defects to optimize properties and harnessing them to tailor the electronic structure for specific applications. We study Cd₃As₂ using a combination of molecular beam epitaxy and magnetoresistance measurements and demonstrate control over the Fermi level and scattering potentials of Cd₃As₂ thin films using tuning parameters uniquely accessible via epitaxial growth. In particular we study the formation of As vacancies, how they impact the electron concentration, and develop strategies to control them.