Capacitance spectroscopy of CdTe self-assembled quantum dots embedded in ZnTe matrix

In this study the capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements have been performed on ZnTe (p-type)-Ti/Au Schottky diodes containing one layer of CdTe self-assembled quantum dots (SAQDs). The reference sample was the ZnTe-Ti/Au diode without dots. Both samples were grown by molecular beam epitaxy technique. The dots were formed during the Stranski-Krastanov growth mode. DLTS measurements for the sample with QDs reveal the presence of two hole-related signals with thermal activation energies equal to E-H1 = 0.2 eV and E-H2 = 0.4 eV. For the reference ZnTe-Ti/Au diode only the H2 signal is observed. It may be concluded that the H1 = 0.2 eV level can be assigned to the hole emission from the QDs. The 0.4 eV trap is attributed to the ZnTe bulk material. (C) 2009 Elsevier B.V. All rights reserved.