Strongly bound Mott-Wannier Excitons in GeS and GeSe monolayers

Abstract

The excitonic spectra of single layer GeS and GeSe are predicted by ab initio GW-Bethe Salpeter equation calculations. G 0 W 0 calculations for the band structures find a fundamental band gap of 2.85 eV for GeS and 1.70 eV for GeSe monolayer. However, excitons are tightly bound, specially in GeS at the Γ point, where the quasi-particle interactions are so strong that they shift the Γ exciton peak energy into the visible range and below the off-Γ exciton peak. The lowest energy excitons in both materials are excited by light along the zigzag direction and have exciton binding energies of 1.05 eV and 0.4 eV, respectively, but despite the strong binding, the calculated binding energies are in agreement with a Mott-Wannier model.

References in corpus (6)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Probing Excitonic Dark States in Single-layer Tungsten Disulfide
• Exciton Binding Energy of Monolayer WS2
• Non-linear Optical Spectroscopy of Excited Exciton States for Efficient Valley Coherence Generation in WSe2 Monolayers
• Excitons in anisotropic 2D semiconducting crystals

Cited by in corpus (4)

• Layered material GeSe and vertical GeSe/MoS2 p-n heterojunctions
• Experimental formation of monolayer group-IV monochalcogenides
• Group-IV monochalcogenide monolayers: two-dimensional ferroelectrics with weak intra-layer bonds and a phosphorene-like monolayer dissociation energy
• Localized Excitons in Defective Monolayer Germanium Selenide