Tightly bound excitons in two-dimensional semiconductors with a flat valence band

Abstract

This theoretical paper offers an explicit expression for the binding energy of excitons in a two-dimensional semiconductor with a flat valence band. The formula has been derived quasiclassically assuming that the exciton is tightly bound; i.e., its ground-state radius is determined by the intrinsic polarizability of the semiconductor rather than by the dielectric properties of the environment. The model is relevant to a few two-dimensional semiconductors discovered recently, including distorted 1T-TiSe${}_2$, with a supposedly unstable electronic ground state. The valence band flatness reduces the exciton binding energy, which also may have an effect on the phase transition to an excitonic insulator.

7 pages, published in Phys. Rev. B with minor corrections

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Cited by in corpus (4)

• Collective Excitations in 2D Materials
• Generalized scaling law for exciton binding energy in two-dimensional materials
• Valley-contrasting interband transitions and excitons in symmetrically biased dice model
• Interlayer excitonic insulator in two-dimensional double-layer semiconductor junctions: An explicitly solvable model