Probing electron probability-density in parabolic quantum wells

Energy spectroscopy of electron states in parabolic quantum wells is done with low-temperature magnetotransport. Introducing a highly-localized potential spike in the middle of the well, we investigate differences of quantum-mechanical probability-density distributions in the presence of electron screening. This is achieved by measuring the spike-induced energy shift and using first-order perturbation theory. With front- and back-gate electrodes, the electron density as well as the position of the electron gas relative to the spike can be tuned. The results are in good agreement with self-consistently calculated wave functions. (C) 1997 Elsevier Science B.V. All rights reserved.