Nucleation and growth of cobalt films on NaCl. III. The effect of substrate temperature

The substrate temperature influences the initial crystal structure of nuclei and determines the thermal energy available for coalescence and recrystallization during film growth, which in turn determines the crystal structure, orientation, and grain size of the final film. Accordingly a substrate temperature of 20 °C favors the growth of polycrystalline h.c.p. films with a small average grain size; and high substrate temperatures (350 and 425 °C) favor the formation and growth of predominantly f.c.c films with either a large average grain size or a single crystal epitaxial overgrowth. A transition between the low- and high-temperature growth behavior is found to occur at a substrate temperature of 200 °C. In this case polycrystalline films of intermediate grain size and with equal numbers of h.c.p. and f.c.c. grains are formed.