Beyond the Anderson rule: importance of interfacial dipole and hybridization in van der Waals heterostructures
- Univ. of Sao Paulo (Brazil); Rensselaer Polytechnic Inst., Troy, NY (United States); Rensselaer Polytechnic Institute
- Univ. of Sao Paulo (Brazil)
- Rensselaer Polytechnic Inst., Troy, NY (United States)
Vertical stacking of two-dimensional materials with weak van der Waals (vdW) interactions has laid the ground for breakthroughs in physics as well as in technological applications. Although vdW interactions dominate interlayer binding, interlayer electronic coupling may not be negligible and can lead to properties beyond the superposition of constituent monolayers. Here, studying heterobilayers of transition-metal dichalcogenides (MQ2; M = Mo, Ni, Pt; Q = S, Se) by means of density functional theory calculations, we show two mechanisms that influence the band gaps of vdW heterostructures beyond the Anderson rule: (1) interfacial hybridization (mainly involving out-of-plane states, such as chalcogen pz-states), which leads to an upshift in the valence band maxima and accordingly a decrease in the band gap. (2) Formation of an interfacial electric dipole, resulting in an effective gap increase in type-II junctions. While the former is material specific, depending on the proximity of pz-states to each other and the valence band maxima, the latter can be generally described using a model based on the charge density decay outside the monolayers and the pristine band edge positions with respect to the vacuum level, irrespective of junction type.
- Research Organization:
- Rensselaer Polytechnic Inst., Troy, NY (United States)
- Sponsoring Organization:
- ANP; FAPESP; USDOE Office of Science (SC)
- Grant/Contract Number:
- AC02-05CH11231; SC0002623
- OSTI ID:
- 1831772
- Alternate ID(s):
- OSTI ID: 23156046
- Journal Information:
- 2D Materials, Journal Name: 2D Materials Journal Issue: 4 Vol. 8; ISSN 2053-1583
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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