Deep level defects of InAs quantum dots grown on GaAs by molecular beam epitaxy

Abstract

The quantum dots (QDs) on S.I. GaAs were grown through the self-assembled growth by molecular beam epitaxy (MBE) and capped with GaAs of 80 nm. The densities of QDs were 3×10 10–6×10 10 cm −2 and their width about 31–34 nm. The deep level defects for samples with InAs QDs were investigated using the photoinduced current transient spectroscopy (PICTS) technique to investigate the lateral transport of the QDs sample. It was found that there are six deep levels in the range from 127 meV to 532 meV in the sample with QDs and their capture cross sections are about 1.6–7.9×10 −15 cm 2. Especially, two deep levels, of which activation energies are 127 and 156 meV below the conduction band edge, might be the defect related with QDs. These defects are thought to be due to the defect related with the excess As atom or In vacancies near the QDs.