Résumé
Our paper is a first step towards tunnelling spectroscopy of individual X-minimum-related shallow donors. We investigated I-V characteristics of submicrometer mesa structures made on GaAs/AlAs/GaAs wafers delta-doped with silicon in the middle of AlAs layer. At 4.2 K and magnetic field up to 6 T we resolved well-separated peaks attributed to resonant tunnelling via individual donors. (C) 2002 Elsevier Science B.V. All rights reserved.