Electrical Transport of Zn-doped Dirac Semimetal Cd₃As₂ Films

Topological semimetals (TSMs) are emerging as materials with potential use in low powered electronics and spintronic devices but detailed studies focusing on reliable epitaxial growth, disorder, and the control of electronic states in TSM films are needed. In this work we focus on the use of alloying with Zn to modify the electronic structure and electrical transport of (Cd_1-xZn_x)₃As₂ with x = 0 - 0.23. Zn doping of Cd₃As₂ has been used to lower the carrier concentration and move the Fermi energy closer to the Dirac point but significant Zn doping causes a transition from a TSM to a semiconductor [1]. By tuning the growth conditions to suppress native defects [2] we are able to produce films with carrier concentrations a full order of magnitude smaller (~10¹⁷ cm^-3) than other literature reports (>10¹⁸ cm^-3). Lowering the starting carrier concentration enables us to tune the Fermi energy with smaller amounts of Zn doping. We will present a careful analysis of the electrical transport properties to explore the low Zn doping regime where the n-type carrier densities reach their lowest values before the electronic structure is significantly altered.

[1] H. Li, et. al., Sci. Rep. 7, 3148 (2017).

[2] A. D. Rice, et. al., PRM. 3, 121201(R) (2019).