Effect of capping on the Dirac semimetal Cd₃As₂ on Si grown via molecular beam epitaxy

Abstract Given the promising applications of large magnetoresistance in the Dirac semimetal cadmium arsenide (Cd₃As₂), extensive research into Si-compatible Cd₃As₂ devices is highly desirable. To prevent surface degradation and oxidation, the implementation of a protection layer on Cd₃As₂ is imperative. In this study, two vastly different protecting layers were prepared on top of two Cd₃As₂ samples. A zinc telluride layer was grown on top of one Cd₃As₂ film, giving rise to a ten-fold increased mobility, compared to that of the pristine Cd₃As₂ sample. Interestingly, unusual negative magnetoresistance is observed in the hexagonal boron nitride-capped Cd₃As₂ device when a magnetic field is applied perpendicularly to the Cd₃As₂ plane. This is in sharp contrast to the chiral anomaly that requires a magnetic field parallel to the Cd₃As₂ plane. We suggest that a protection layer on molecular beam epitaxy-grown Cd₃As₂ should be useful for realising its great device applications in magnetic sensing.