Tuning Between Quantum-Dot- and Quantum-Well-Like Behaviors in Type II ZnTe Submonolayer Quantum Dots by Controlling Tellurium Flux During MBE Growth

We report tuning of properties of type II nanostructures between quantum dot (QD)-like and quantum well (QW)-like behaviors in ZnSe layers with ZnTe submonolayer insertions, grown by migration-enhanced epitaxy. The sizes of QDs are estimated from magneto-photoluminescence (PL) measurements, which showed no significant change in the QD lateral size with increasing Te flux, indicating increase in QD density instead. The area density of QDs is estimated from the results of secondary-ion mass spectrometry measurements. It is determined that, in the sample grown using the highest Te flux, the electronic wavefunctions begin to overlap, leading to QW-like behavior before the formation of a full QW layer. This is also confirmed via temperature-dependent time-resolved PL, which showed significant change of excitonic lifetimes and binding energies of type II excitons.