Experimental and theoretical studies of single Pb atom dynamics in one Si(111)-(7×7) unit cell

The theoretical simulation of single Pb atom motion in faulted and unfaulted halves of a Si(1 1 1)-(7 × 7) surface were performed using the kinetic Monte Carlo method. Modifying diffusion barriers within the unit cell, the results were fitted to STM observations over a wide temperature range between 50 and 300 K. The average activation energy of a single atom jump was estimated to be approximately 0.1–0.2 eV, giving a diffusion coefficient of ≈3 × 10 −5 cm 2 s −1 at 300 K inside the Si(1 1 1)-(7 × 7) unit cell.