Type-Ⅱ recombination dynamics of tensile-strained GaP quantum dots in GaAs grown by droplet epitaxy

摘要

We use droplet epitaxy to create tensile-strained GaP quantum dots in a GaAs matrix. A strong biaxial tensile strain leads to the formation of a type-Ⅱ band lineup with a transition energy lower than the bulk GaAs band gap. The luminescence transients exhibit highly non-exponential decay behavior with an average time constant of 11 ± 2 μs, which is more than three orders of magnitude longer than the lifetime of standard type-Ⅰ quantum dots. The prolonged luminescence decay time for the GaP/GaAs dots confirms the formation of the type-Ⅱ band alignment associated with the tensile strain.