Abstract
The photoluminescence (PL) and PL excitation (PLE) spectra of MOCVD grown double heterostructures GaN/InGaN/GaN with InN concentration in the solution range 0.4–2% were studied within the temperature interval 2–300 K. A fine structure of the PL band found at T = 2 K is attributed to exciton localization at small In clusters of size s = 2 and 3 in the cation sublattice. The temperature variation of the PL spectra shows that the PL band maximum position ϵmaxPL(T) follows either “normal” or “anomalous” (“S-shaped”) behavior in dependence on the concentration of In. We argue that the anomalous behavior is due to long-living excited (metastable) states of fractal-like complexes of s = 2 clusters which occur in the region of the mobility edge due to a random spatial distribution of clusters and participate in the formation of the high energy part of the PL band. Their small relaxation rate at lowest temperatures and their high sensitivity to the temperature variation are considered as the reason of the “anomalous” behavior of PL bands.
Published Version
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