Strong carrier confinement inInxGa1−xN∕GaNquantum dots grown by molecular beam epitaxy

We report photoluminescence and time-resolved photoluminescence experiments on ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}∕\mathrm{Ga}\mathrm{N}$ quantum dots grown by plasma-assisted molecular beam epitaxy. We show photoluminescence from single quantum dots, giving an unambiguous proof of the quantum dot nature of luminescence. In addition, we show that both the photoluminescence intensity and the carrier recombination time remain constant up to $200\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, reflecting the strong confinement of the carriers inside the quantum dots. We find monoexponential photoluminescence decay times as short as $340\phantom{\rule{0.3em}{0ex}}\mathrm{ps}$, explained by the lack of the quantum confined Stark effect in our structures.