InMnP:Zn epilayers doped with Mn (0.290 at.%) were annealed at 723-873 K for 60 s and 473-573 K for 30 min. Using Auger electron spectroscopy, the changes in concentration profiles of the epilayers correlated to the ferromagnetic origin as a function of the annealing conditions. The epilayers annealed at 723-873 K for 60 s exhibited InMn3 persisting up to 583 K. For InMnP:Zn epilayers annealed at 523-573 K for 30 min, the concentration depth profiles remained flat so that the stoichiometry was well maintained without precipitates such as InMn3 and MnP comparable to the as-grown InP:Zn before doping Mn. These samples showed clear ferromagnetic hysteresis loops. Curie temperature was about 150 K. A ferromagnetic hysteresis loop was obtained even at very lower annealing temperature of 473 K. (c) 2007 Published by Elsevier B.V.