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 by on top of two Cd3As2 samples. A zinc telluride layer was grown on top of one Cd3As2 film, giving rise to an ten-fold increased mobility, compared to that of the pristine Cd3As2 sample. Interestingly, unusual negative magnetoresistance is observed in the hexagonal boron nitride (h-BN)-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 MBE-grown Cd3As2 should be useful for realizing its great device applications in magnetic sensing.