Deep Levels Induced by CdTe/ZnTe Quantum Dots

E. Zielonya, E. Placzek-Popkoa, A. Roznickaa, Z. Gumiennya, J. Szatkowskia, P. Dybaa, W. Pacuskib, c, C. Krusec, D. Hommelc and M. Guziewiczd aInstitute of Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland bInstitute of Experimental Physics, University of Warsaw, Hoża 69, 00-681 Warsaw, Poland cInstitute of Solid State Physics, University of Bremen, Postfach 330 440, D-28334 Bremen, Germany dInstitute of Electron Technology, al. Lotników 32/46, 02-668 Warsaw, Poland

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The electrical properties of the CdTe/ZnTe quantum dot system have been analyzed to identify deep-level defects related with the presence of quantum dots. The capacitance-voltage (C-V) and deep level transient spectroscopy measurements were used to investigate the samples. A reference ZnTe sample (without dots) was also studied for comparison. Both samples were grown by molecular beam epitaxy technique on the n-type GaAs substrate. The quantum dots were formed by a Zn-induced reorganization of a thin CdTe layer. The presence of quantum dot formation was confirmed by micro-photoluminescence measurements. The deep level transient spectra for both samples are complex. In order to characterize individual contributions to the deep level transient spectra the latter have been simulated by separated Gaussian components [1]. The results of the deep level transient spectroscopy measurements yield the conclusion that the same defects are present in both materials but there is an increased concentration of the defects in the quantum dot structures. No deep level associated directly with the quantum dot confinement has been identified.

DOI: 10.12693/APhysPolA.119.630 PACS numbers: 73.61.Ga, 73.21.La, 73.20.Hb