Decay of silicon mounds: Scaling laws and description with continuum step parameters

The decay of mounds about a dozen layers high on the Si(111)-(7 X 7) surfac e has been measured quantitatively by scanning tunneling microscopy and com pared with analytic predictions fur the power-law dependence on time predic ted for a step-mediated decay mechanism. Conformably, we find an exponent 1 /4 associated with the (3D) decay of the mound height and exponent 1/3 asso ciated with the (2D) decay of top-layer islands. Using parameters from a co ntinuum step model, we capture the essence of the kinetics. Qualitative fea tures distinguish these mounds from multilayer islands found on metals.