Phase diagram and crystal growth of Mn-substituted CuInSe2 system and their defect properties Original Research Article

In order to obtain newer materials with better diluted magnetic semiconductor (DMS) performance, we have constructed the phase diagrams of Mn-substituted CuInSe2 systems, using differential thermal analysis and powder X-ray diffraction. Based on these phase diagrams, which show that the Mn-substituted CuInSe2 solid solutions are obtained, bulk crystals were grown by the horizontal gradient freezing method. The grown crystals substituted by Mn atom in Cu- and In-site have compositional homogeneity, and n- and p-type conductions, respectively, and seem to become a degenerated semiconductor for heavy Mn doping. The optical band gaps of the crystals substituted by Mn atom in Cu- and In-site were a little larger and narrower, respectively, than that of non-doped CuInSe2. The changes of electrical and optical properties indicated that Mn atoms were certainly substituted for two kinds of cations in CuInSe2.