The influence of a rapid thermal annealing procedure on the properties of Ga(N,As,P) multiple quantum wells grown on silicon substrates has been studied. We reveal the changes in composition and disorder on the basis of photoluminescence, photoluminescence excitation and Raman spectroscopy as well as transmission electron microscopy. The optimal annealing temperature was found to be in the range of 900-925 degrees C. By increasing the annealing temperature (T-a) from 850 degrees C to 1000 degrees C. we found a gradual exchange of arsenic and phosphorous atoms between the quantum wells and the barriers. At highest annealing temperatures our results are consistent with a reduction of the As concentration by several percent. (C) 2014 Elsevier B.V. All rights reserved,