Atomic equilibrium concentrations in (InGa)As quantum dots

In InxGa1-xAs quantum dots (QDs), the plot of peak emission energies versus the total amount of indium exhibits a well defined pattern, which is independent of the indium concentration. Moreover, photoluminescence spectra of InAs QDs grown by atomic layer molecular beam epitaxy (ALMBE) roughly coincide with those of In"Ga0.5As QDs grown by metalorganic vapor phase deposition. We suggest that the total amount of In rather than the nominal In concentration determines the emission energy of these two sets of QDs, and that In interdiffusion is rather strong in ALMBE growth.