Study of electrically active defects in GaAs/InAs/GaAs QDs structures by DLTS and TEM

The apparent C-V profiles and the deep levels in GaAs/InAs/GaAs quantum dot nanostructure, have been investigated by space charge spectroscopy techniques (C-V and DLTS). Accumulation peaks and/or depletion of free carriers at the QDs plane are observed under the considered growth parameters. It is shown that, both in the cap and at the QD-layer/cap interface, the deposition of lnAs QDs induces deep levels which exhibit a logarithmic dependence of the DLTS signal amplitude from the pulse width. transmission electron microscopy (TEM) analysis shows extended defects in the cap and near the QD/cap interface, which have been correlated to electrical measurement results