Controllable p–n junctions in three-dimensional Dirac semimetal Cd₃As₂ nanowires

We demonstrate a controllable p−n junction in a three-dimensional Dirac semimetal (DSM) Cd₃As₂ nanowire with two recessed bottom gates. The device exhibits four different conductance regimes with gate voltages, the unipolar (n−n and p−p) and bipolar (n−p and n−p) regimes, where p−n junctions are formed. The conductance in the p−n junction regimes decreases drastically when a magnetic field is applied perpendicular to the nanowire. In these regimes, the device shows quantum dot behavior, whereas the device exhibits conductance plateaus in the n−n regime at high magnetic fields. Our experiment shows that the ambipolar tunability of DSM nanowires can enable the realization of quantum devices based on quantum dots and electron optics. (paper)