Exciton Binding Energy in Finite Spherical GaAs/GaAlAs Quantum Dots under an Intense THz Laser Field

Abstract

In this work, we study the ground-state binding energy of heavy-hole excitons in finite spherical GaAs/GaAlAs quantum dots at the very high terahertz laser field. The interaction with the radiation is described by a laser-dressed Coulomb potential in which the electron-hole attraction is modified by the field displacement of the charge carriers. We calculate the excitonic states in the single-band effective mass approximation using a variational method. We find that the electron and hole confinement-energy contributions are initially increasing with the laser-dressing parameter and become saturated. For all the dot radii considered, the exciton binding energy decreases and the decrease is more pronounced in larger quantum dots. Small dots tend to bind with stronger binding because we are in geometric confinement, the electron-hole wavefunction overlap is larger. The statement that the laser “attracts the exciton towards the dot center and stabilizes it” should be removed unless your calculations explicitly show this. Your results suggest that the electron-hole separation is increasing and the excitonic state weakens.