Marsen, B.; Klemz, S.; Landi, G.; Steinkopf, L.; Scheer, R.; Schorr, S.; Schock, H.-W.: Phases in copper-gallium-metal-sulfide films (metal=titanium, iron, or tin). Thin Solid Films 519 (2011), p. 7284-7287
10.1016/j.tsf.2011.01.137
Abstract:
The incorporation of metal impurities M (M=Ti, Fe, or Sn) into CuGaS2 films is investigated experimentally as a function of impurity concentration. Films are synthesized by thermal co-evaporation of the elements onto glass/Mo substrates heated to 400°C-570°C. The compositions of the resulting films are measured by energy-dispersive x-ray spectroscopy and the structures of the present phases are studied by x-ray diffraction. The formation of Cu-M-S ternary phases is observed in a wide range of conditions. Films of Cu-Ga-Ti-S, synthesized at 500°C, show the presence of a cubic modification of CuGaS2 and Cu4TiS4. Alloying of CuGaS2 and tetragonal Cu2SnS3 is observed for substrate temperatures of 450°C. A miscibility gap opens at 500°C and above with separate Sn-rich and Ga-rich phases. Similarly, alloys of CuFeS2 and CuGaS2 are only found in Cu-Ga-Fe-S films synthesized at lower substrate temperature (400°C), whereas at 500°C a miscibility gap opens leading to separate Fe-rich and Ga-rich phases.