Carrier Dynamics and Dynamic Band-Bending in Type-II ZnTe/ZnSe Quantum Dots

Abstract

Carrier dynamics and dynamic band-bending in self-assembled ZnTe/ZnSe quantum dots have been studied by means of time-resolved photoluminescence experiment at low temperatures. The experiment reveals clearly type-II character of the confinement potential in the dot manifested in: (i) long photoluminescence decay time constant of 28-35 ns, and (ii) temporal shift of the quantum dot peak emission towards low energy following the laser pulse excitation. The magnitude of the spectral shift Delta E depends on the dot size and the power density of excitation pulse. For the dots under study and given experimental conditions Delta E approximate to 28 divided by 42 meV.