Spontaneous emission mechanisms in InGaN alloys were studied by determining the effective band gap energies using photoluminescence excitation spectroscopy and static and time-resolved photoluminescence (PL) measurements on fully strained cubic (c-) InxGa1-xN films on c-GaN templates, which were grown by rf molecular-beam epitaxy on smaller lattice-mismatched 3C-SiC (001) substrates prepared on Si (001). The c-InxGa1-xN alloys exhibited large band gap bowing. The PL decay dynamics showed that the emission is due to recombination of localized excitons, the same as in the case of hexagonal InGaN. The c-InxGa1-xN exhibited a larger Stokes-like shift and a larger localization depth, showing that the material's inhomogeneity is much enhanced compared to that of the hexagonal polytype.
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