Formation of a precursor layer in self-assembled CdTe quantum dots grown on ZnSe by molecular beam epitaxy

摘要

The growth mode of CdTe quantum dots (QDs) grown on highly lattice-mismatched ZnSe buffer was investigated. CdTe QDs (0.6 to 5.0 mono-layers (MLs)) were deposited on the Se-stabilized ZnSe buffer layers using an alternating supply of Cd and Te atomic sources. Cross-sectional transmission electron microscopy and photoluminescence (PL) measurements revealed the existence of a CdSe-like two-dimensional precursor layer (PCL). The prominent difference in the temperature-dependent PL peak shift was associated with the emissions from the respective CdSe PCL and CdTe QDs. In addition, the PL excitation measurement demonstrated the existence of the first QD excited excitonic state.