Electrical characterization of InAs/GaAs quantum dots by frequency spectroscopy

The frequency dependence of differential capacitance from a layer of InAs quantum dots embedded in the space charge region of a GaAs Schottky diode has been investigated. From a theoretical treatment of the thermal capture and emission processes and by comparing with experimental data from deep level transient spectroscopy (DLTS), we demonstrate how the small signal frequency dependence is influenced by the different electron orbitals appearing in the quantum dots. From capacitance spectroscopy data, the width of the distributions for energy levels of the s and the p shells, respectively, is obtained.