Finite-temperature phase diagram of vicinal Si(100) surfaces

The phase diagram of vicinal Si(100) as a function of misorientation angle and temperature is calculated. Contrary to previous suggestions that only double-layer steps should appear on the equilibrium surface, it is predicted that the single-layer stepped surface is at equilibrium for small misorientation angles. This structure is stabilized by strain relaxation and by the thermal roughening of the steps. For annealed surfaces the critical angle at which the transition between the single- and double-layer stepped surface occurs is calculated to be ${\mathrm{\theta }}_{\mathit{c}}$≊2°.