Quantum Confinement of Electron-Phonon Coupling in Graphene Quantum Dots

Abstract

On the basis of first-principles calculations and the special displacement method, we demonstrate the quantum confinement scaling law of the phonon-induced gap renormalization of graphene quantum dots (GQDs). We employ zigzag-edged GQDs with hydrogen passivation and embedded in hexagonal boron nitride. Our calculations for GQDs in the sub-10 nm region reveal strong quantum confinement of the zero-point renormalization ranging from 20 to 250 meV. To obtain these values we introduce a correction to the Allen-Heine theory of temperature-dependent energy levels that arises from the phonon-induced splitting of 2-fold degenerate edge states. This correction amounts to more than 50% of the gap renormalization. We also present momentum-resolved spectral functions of GQDs, which are not reported in previous contributions. Our results lay the foundation to systematically engineer temperature-dependent electronic structures of GQDs for applications in solar cells, electronic transport, and quantum computing devices.

References in corpus (20)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• Energy Gaps in Graphene Nanoribbons
• Spin qubits in graphene quantum dots
• Room temperature magnetic order on zigzag edges of narrow graphene nanoribbons
• Self-passivating edge reconstructions of graphene
• Tuning of energy levels and optical properties of graphene quantum dots
• {\it Ab--initio} finite temperature excitons
• Robustness of edge states in graphene quantum dots
• An On/Off Berry Phase Switch in Circular Graphene Resonators
• The temperature dependence of electronic eigenenergies in the adiabatic harmonic approximation
• Electrostatically confined monolayer graphene quantum dots with orbital and valley splittings
• Predominance of non-adiabatic effects in zero-point renormalization of the electronic band gap
• Comparing electron-phonon coupling strength in diamond, silicon and silicon carbide: First-principles study
• A path-integral molecular dynamics simulation of diamond
• Unified theory of electron-phonon renormalization and phonon-assisted optical absorption
• Diffusion quantum Monte Carlo and GW study of the electronic properties of monolayer and bulk hexagonal boron nitride
• Path-integral molecular dynamics simulation of 3C-SiC
• Quantum confinement of Dirac quasiparticles in graphene patterned with subnanometer precision
• Temperature dependence of the optical properties of silicon nanocrystals