Remarkable coincidence between the steps of themagneto-luminescence energy and the plateaus of theQuantum Hall Effect in modulation-doped GaAs/GaAlAsquantum wells

摘要

Photoluminescence (PL) experiments were carried out on asymmetric modulationrndoped GaAs/Ga0.67Al0.33As single quantum wells (QW) in order to elucidate the origin ofrnnonlinear behavior of interband optical energies as functions of an external magnetic fieldrnB. The Quantum Hall Effect (QHE) was measured on the same samples under illumination.rnA remarkable coincidence was found between the nonlinearities of PL energies and onsetsrnof the quantum Hall plateaus. The PL experiments were also carried out on asymmetricrnQWs having the same 2D electron density but different widths. These experimental data arerndiscussed using two models: 1) The standard explanation of nonlinearities as resulting fromrnthe screened exchange and correlation effects in electron and hole 2D subbands; 2) A modelrnin which the nonlinearities are caused by an oscillatory change of 2D electron density Nu000b inrnthe QW as a function of B. It is found that the model of screened exchange and correlationrnis in contradiction with our experiments on QWs of different widths. On the basis of ourrnresults, as well as those of other authors, we conclude that it is the oscillatory behavior of thernelectron density Nu000b (B) in the QW that provides adequate description of the existing data onrnthe nonlinearities of the PL energies.