Long-lived excitons up to 1 μs in GaN/AlN self-assembled quantum dots

We report the observation of long-lived excitons in GaN/AIN self-assembled quantum dots at the temperature of 3.5 K. The PL decay time strongly increases and reaches Its order with increasing size of the QDs. This strongly suggests that the PL decay is almost free from non-radiative processes and dominated by radiative recombination processes in the GaN QDs. The increase of the PL decay time with increasing size of the QDs originates from the reduction of the oscillator strength due to the strong built-in electric field in the GaN/AIN heterostructures. (C) 2003 WILEY-VCH Veflag GmbH & Co. KGaA, Weinheim.