Scanning Microscopy


We present an experimental and theoretical study of the carrier capture time into a semiconductor quantum well. The carrier capture time was obtained by measuring both the rise of the quantum well (QW) population using time-resolved luminescence measurements and the decay of the barrier population using pump-probe correlation experiments. In the first technique, we compare the QW rise-times after direct (below the barrier band gap) and indirect (above the barrier band gap) excitation in order to eliminate the effects of relaxation and exciton formation in the quantum well.

We report the first experimental observation of oscillations in the carrier capture time between 3 and 20 ps as a function of quantum well thickness, obtained from both techniques. The observed capture times are, for the first time, in agreement with theoretical predictions from an ambipolar capture model.

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