Tunable excitons in gated graphene systems

Abstract

We develop a microscopic theory of a strong electromagnetic radiation interaction with bilayer graphene where an energy gap is opened by a static electric field perpendicular to graphene planes. We show that an adiabatic changing on time of the gate potentials (that leads to the resonance of the energy gap with electromagnetic field) may produce full inversion of the electron population between valence and conduction bands. Quantum kinetic equations for density matrix are obtained by the use of a tight-binding approach within second quantized Hamiltonian in an intense laser field and taking into account Coulomb correlations between particles. Excitonic absorption in graphene systems (monolayer and bilayer) with opened energy gap is investigated for different values of the gap and the parameters describing the band structure. © 2016 SPIE.