Although ZnTe and CdSe exhibit similar characteristics in terms of the penetration of MIGS and the band gap evolution with barrier thickness, they significantly differ in their band edge positions. For the ZnTe barrier, the valence band maximum is aligned with that of the InAs, similar to the bilayer interface (Figure ). Once the ZnTe barrier becomes thick enough to fully develop a band gap (Figure ) the Fermi level is positioned approximately in the center of the gap, similar to the bilayer interface with Al (Figure ). This means that ZnTe forms an effective barrier for electrons. Owing to the slight downward band bending, a small barrier for holes is also present in Figure . For the CdSe barrier, the conduction band minimum is aligned with that of the InAs, similar to the bilayer interface (Figure ). Regardless of the barrier thickness, the Fermi level is positioned in the CdSe conduction band, similar to the bilayer interface with Al (Figure ). As a result, CdSe forms an effective barrier for holes but no barrier for electrons. In InAs-based Majorana devices, there is only electron transport because of Fermi level pinning in the conduction band at the InAs surface. Therefore, of the two materials considered here, ZnTe is the better candidate.