Ultrahigh vacuum scanning tunnelling microscopy studies of the decapped InAs quantum dots on GaAs(001) surface after desorption of a protective as layer

The morphology and electronic properties of InAs quantum dots (QDs) on the GaAs(001) surface has been studied by ultrahigh vacuum scanning tunnelling microscopy/spectroscopy after removal of a preliminary deposited protective As layer, A thermal annealing procedure has been developed, which, applied to a sample with an As cap layer, allows InAs QDs to be opened on the surf ace of an InAs wetting layer (WL) exhibiting a [2 x 4] reconstruction of As dimers, Scanning tunnelling spectroscopy measurements on the decapped surf ace show that I-V characteristics taken with the microscope tip positioned over single InAs QDs have a smaller voltage width for zero conductivity (dI /dV V = 0) when compared with those taken over the InAs WL, which are essen tial the same as the I-V characteristics for a clean GaAs surface. This obs ervation seems to indicate a weakening of the surface band bending in the a reas beneath InAs QDs. Copyright (C) 1999 John Wiley & Sons, Ltd.