Thermal step bunching on the restricted solid-on-solid model with point contact inter-step attractions

Abstract We present the restricted solid-on-solid (RSOS) model with the inter-ledge interaction of the point contact type (p-RSOS model). We have made detailed calculation of the Andreev free energy f ˜ ( η x , η y ) , which is similar to the equilibrium crystal shape (ECS) z = z ( x , y ) , and the surface gradient p → = ( p x , p y ) = ( ∂ z / ∂ x , ∂ z / ∂ y ) as the function of the Andreev field η → . From the calculated f ˜ ( η x , η y ) and p → ( η → ) , we have obtained the vicinal surface free energy f ( p → ) . The inter-ledge attraction between adjacent steps affects the surface free energies in the equilibrium, and causes the first-order transition on the profile of ECS at low temperature. The inter-ledge attraction also destabilizes the regular train of steps. We also have obtained the thermal step bunching.