Tunable electronic properties, band alignments, and charge transfer of ferroelectric MoSi2N4/In2Se3 van der Waals heterostructures

Van der Waals heterostructures (VDWHs) have been used to engineer novel electronic properties of two-dimensional (2D) material systems in recent years. Leveraging the excellent mechanical and electronic properties of MoSi2N4 and the ferroelectric properties of 2D α-In2Se3, we investigate how these materials interact via first-principles calculations. We find that these VDWHs have different bandgap types and nature under different polarizations. We apply vertical strain or biaxial strain to both polarizations for bandgap modulation. We find that both polarizations are highly tunable, exhibiting a variety of behaviors, such as the type-II-to-type-H band alignment, large bandgap changes, and the direct-to-indirect bandgap transitions. Interestingly, we also find that both orientations possibly undergo a topological phase transition under −8% biaxial strain. From transmission coefficient calculations, we expect devices made from our heterostructures to exhibit low leakage current and high on/off ratios suitable for low power circuits. These findings, hence, demonstrate another viable option toward ferroelectric devices based on MoSi2N4 VDWH. In particular, we find that our heterostructures bandgaps can be adjusted closer to visible light, offer compelling options for ferroelectric solar cells and transistors.