Nucleation and growth kinetics of spiral steps on TiN(111): An in situ low-energy electron microscopy study

Abstract

We use in situ low-energy electron microscopy to investigate the near-equilibrium dynamics of TiN(111) steps, pinned by surface-terminated dislocations, as a function of N2 pressure pN2 and time during annealing of TiN(111) layers at temperatures T between 1600 and 1735 K. At each T, we observe the nucleation and growth of spiral steps rotating around dislocation cores. The spirals undergo a shape-preserving motion with a constant angular velocity ω as they grow inward, normal to the surface, forming vacancy pits. We find that ω for successive spirals emanating from the same source decreases slowly with time at all pN2 values between vacuum and 5×10−7Torr. From the ω(T) data, we obtain an activation energy of 4.6±0.2eV, irrespective of pN2, for the growth of spiral steps.