In this work we investigate the role of surface steps during annealing of InP(001) surfaces and nucleation of thin InP films. In-air atomic force microscopy was used to analyse the morphology of the InP surfaces. InP substrates with different miscuts were annealed at 530 degrees C, for different time intervals. Equilibrium state was reached only for the nominally-oriented surface. We show here that this procedure can lead to the formation of multi-step structures on the misoriented surfaces, suggesting a strong step-step interaction during annealing. Analysing the morphologies of thin (less than or equal to 10 nm thick) InP films grown on the annealed substrates we have observed that the misoriented surfaces, specially those showing a larger density of B-steps, present a behaviour completely different from nominally oriented InP(001) surfaces, suggesting the presence of a barrier for adatom movement across B-step edges. (C) 1998 Elsevier Science B.V. All rights reserved.191416714450