Properties of Excitons Bound to Neutral Donors in GaAs Quantum-Well Wires

In the effective mass approximation, the binding energy of an exciton bound to a neutral donor (D⁰, X) is calculated variationally for rectangular GaAs quantum-well wires (QWWs) by using a three-parameter wavefunction. The Coulomb interaction terms are treated exactly in their full three-dimensional forms throughout the calculation, especially in the case of (D⁰, X), which is a more physically realistic procedure than those employed in previous calculations which used effective one-dimensional potential Chin. Phys. Lett. 21 (2004) 919. Our treatment is unique in the use of a two-dimensional Fourier expansion of the Coulomb potential, which removes the numerical difficulty with the 1/r singularity and considerably reduces the computational effort. In addition, we also calculate the binding energies of (D⁰, X) when the donor is in different positions (at the centre, boundary and corner). The average interparticle distances in the square QWWs are discussed.