Carrier transfer between InGaAs/GaAs quantum wells separated by thick barriers

We have studied the carrier transfer between two adjacent wells of different width separated by a 100 nm thick barrier. At low temperatures (T < 30 K) the transfer has very little dependence (if any) on T. For T > 30 K: the transfer strongly increases, denoting that the thermal escape out of the QW becomes the main mechanism. Finally, a drastic quenching of the transfer is found for temperatures higher than 50 to 70 K, suggesting the activation of a further non-radiative channel different from the thermal escape.