Doping controlled Fano resonance in bilayer 1T${}^{\prime }$-ReS${}_2$: Raman experiments and first-principles theoretical analysis

Abstract

In the bilayer ReS${}_2$ channel of a field-effect transistor (FET), we demonstrate using Raman spectroscopy that electron doping (n) results in softening of frequency and broadening of linewidth of the in-plane vibrational modes, leaving out-of-plane vibrational modes unaffected. Largest change is observed for the in-plane Raman mode at $\sim$ 151 cm${}^{-1}$, which also shows doping induced Fano resonance with the Fano parameter 1/q = -0.17 at doping concentration of $\sim 3.7\times 10^{13}$ cm${}^{-2}$. A quantitative understanding of our results is provided by first-principles density functional theory (DFT), showing that the electron-phonon coupling (EPC) of in-plane modes is stronger than that of out-of-plane modes, and its variation with doping is independent of the layer stacking. The origin of large EPC is traced to 1T to 1T${}^{\prime }$ structural phase transition of ReS${}_2$ involving in-plane displacement of atoms whose instability is driven by the nested Fermi surface of the 1T structure. Results are also compared with the isostructural trilayer ReSe${}_2$.

References in corpus (6)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Electrochemically Top Gated Graphene: Monitoring Dopants by Raman Scattering
• Symmetry-dependent phonon renormalization in monolayer MoS2 transistor
• Disorder engineering and conductivity dome in ReS2 with electrolyte gating
• A high-mobility electronic system at an electrolyte-gated oxide surface
• Anomalous phonon redshift in K-doped BaFe2As2 iron pnictides