The effects of monovacancies on the terrace width during sublimation from the (111) surface of a diamond-like crystal

Using the three-dimensional Monte Carlo model, the effect of monovacancies on the diffusion exchange between the steps on the (111) surface of a diamond-like crystal during sublimation was investigated. The critical terrace width L_cr (the distance from the step edge to the nearest stable vacancy islands) was determined as a function of the relationship between the energy of adatom formation at the smooth terrace E_n and the energy of adatom desorption from the terrace E_d with retention of the sum of these energies E_sub=E_n+E_d, which characterizes the sublimation of a substance. A well-pronounced maximum exists in the dependences L_cr(E_n) obtained. The formula is suggested which well describes the dependences L_cr(E_n) for various values of E_sub. The extrapolation of the dependence L_cr(E_n) to the value E_sub=4.2 eV, which is characteristic of Si, permits us to compare the model results with the experimental data of other authors. The explanation of a threefold increase in the terrace width, which is observed experimentally at about 1500 K, is suggested.