Roughness of vicinal surface is studied by calculating surface width using the Monte Carlo Method in the non-equilibrium steady state in order to clarify discrepancies between theoretical results and experiments. The adopted model is a restricted solid-on-solid (RSOS) model with a discrete Hamiltonian. Here, “restricted” means that the surface-height difference between nearest-neighbor sites is restricted to 0, and ±1. The temperature T, driving force for growth Δμ, system size L, and surface slope dependences of the surface width g^(1/2)W are calculated for vicinal surfaces tilted between the (001) and (111) surfaces Initial 2×10^8 Monte Carlo step/site (MCS/site) are discarded. Surface width is averaged over following 2×10^8 MCS/site. We found a crossover from a Berezinskii–Kosterlitz–Thouless (BKT) rough surface to a Kardar–Parisi–Zhang (KPZ) rough surface. We also found that the crossover point from a BKT (logarithmic) rough surface to a KPZ (algebraic) rough surface is different from the kinetic roughening point for the (001) surface. Ad-atoms, ad-holes, islands, and negative-islands on the surface are found to block surface fluctuations, which contributes to making a BKT-rough surface.
