InGaAs tunnel-injection structures with nanobridges: Excitation transfer and luminescence kinetics

Methods of optical spectroscopy and electron microscopy have been used to study tunnel-injection nanostructures the active region of which consisted of an upper In 0.15 Ga 0.85 As quantum-well layer and a lower layer of In 0.6 Ga 0.4 As quantum dots as a light emitter; both layers were separated by a GaAs barrier layer. Deviations from the semiclassical Wentzel-Kramers-Brillouin model are observed in the dependence of the tunneling time on barrier’s thickness. Reduction of the transfer time to several picoseconds at a barrier thickness smaller than 6 nm is accounted for by formation of InGaAs nanobridges between tops of quantum dots and the quantum-well layer; the nanobridges include those with their own hole state. The effect of an electric field induced by tunneling on the carriers’ transfer time in a tunnel-injection nanostructure is taken into account.