DLTS Study of InGaAs/InGaAsP Double-layered QDs with Various Spacer Layers

Abstract

We studied the electrical properties of vertically-stacked double-layered InGaAs/InGaAsP quantum dot (QD) systems by performing capacitance-voltage (C-V) and deep-level transient Spectroscopy (DLTS) measurements. The samples had two stacked QD layers with different sizes, with the QD layers being separated by spacer layers with thicknesses of 20 run and 100 rim. In the DLTS measurement for the QD samples, two signals obtained from discrete energy levels of the QDs were analyzed. For the 100-nm-spacer layered QD system, the activation energies of the signals were 0.35 eV and 0.42 eV while for the 20-nm-spacer layered QD system, the activation energies of the signals were 0.36 eV and 0.43 eV, respectively. These activation energies of the QD signals could be varied by changing applied voltage during DLTS measurement.