First principles approach to binding energies of excitons, trions and biexcitons in quantum wells

Abstract

1 Introduction. With recent developments in semiconductor technology quasi one-dimensional and thin-layer structures have attracted much attention. These systems show nontrivial Coulomb correlation effects leading to interesting optical and transport characteristics which are not seen in bulk materials. For example, a strong increase of exciton binding energies has been found experimentally [1] at specific quantum well (QW) widths. Also, crystallization of electrons in quantum dots with a finite number of particles has recently been predicted theoretically using PIMC simulations [5]. In this paper we investigate Coulomb correlations in electron-hole systems in QW’s and clearly show that the observed effect of the increase of the binding energies in these systems is connected with changes in the effective in-plane interaction potential. We develop a novel first-principles approach based on PIMC simulations which does not involve expansions in terms of basis functions or any symmetry assumptions and is, thus, expected to allow for an efficient treatment of complex experimental systems in the future. 2 Quantum well model. We consider a single quantum well consisting of a thin semiconductor film of thickness . In the effective-mass approximation the electron-hole Hamiltonian reads