Transition between quasi 2 and 3D behaviour of the binding energy of screened excitons in semiconducting quantum well structures.

Abstract

We have calculated the binding energy of screened excitons in a semiconducting quantum well structure as a function of screening parameter and the width of the quantum well using variational wave functions to obtain upper bounds for the energy. The binding energy decreases with increasing values of the screening parameter and with increasing well width. However, as long as the well width is narrow enough so the electrons and holes occupy their lowest-energy subbands, the exciton remains bound even for large values of the screening parameter whenever the electron gas remains nondegenerate.