| Popis: |
We have investigated the effect of the internal electric fields on radiative and non-radiative processes in a series of AlN/GaN superlattices. The results of measurements involving direct detection of phonons emitted as a result of non-radiative recombination and carrier energy relaxation are compared with time-resolved photoluminescence studies. Using these complimentary techniques we have observed directly the effect of free carrier screening on the radiative and non-radiative recombination processes in the superlattice samples. We find that, at high excitation power, photoinjected carriers screen the strong internal fields, resulting in an enhanced radiative recombination. As the carriers recombine, the de-screening effect results in an increase in recombination via non-radiative processes, which we observe directly as a delayed phonon signal in the time of flight measurements. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) |
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