Surface self-diffusion of Si on Si(001)

The surface diffusion coefficient of Si atoms on a Si(001) surface is quantitatively determined using scanning tunneling microscopy. The method rests on counting the number of islands that form at various substrate temperatures for a given deposited dose at a given deposition rate. In the simplest situation, the diffusion coefficient is related to the island density by N α D−13 and to the width of denuded zones at steps by WDZαD16. The activation energy for diffusion is Ea = 0.67±0.08 eV an D0≅10−3±1 cm2. The diffusion is highly anisotropic, with the fast direction along the dimer rows.