Exciton States in Wurtzite InGaN Coupled Quantum Dots

Based on the effective-mass approximation, exciton states confined in wurtzite In_xGa_1-xN/GaN strained coupled quantum dots (QDs) are investigated, in which the strong built-in electric field effects due to the piezoelectricity and spontaneous polarization are considered. We find that the barrier thickness between the two QDs has a considerable influence on the exciton states and the interband optical transitions. If the barrier thickness is increased, the exciton binding energy is decreased, the emission wavelength is increased, and the electron--hole recombination rate is obviously reduced. Our theoretical results are in qualitative agreement with the experimental measurements.