Nonclassical smoothening of nanoscale surface corrugations

We report the first experimental observation of nonclassical morphological equilibration of a corrugated crystalline surface. Periodic rippled structures with wavelengths of 290-550 nm were made on Si(001) by sputter rippling and then annealed at 650-750 degrees C. Tn contrast to the classical exponential decay with time, the ripple amplitude A(lambda)(t) followed an inverse linear decay, Al(t) = A(lambda)(0)/(1 + k(lambda)t), agreeing with a prediction of Ozdemir and Zangwill. We measure the activation energy for surface relaxation to be 1.6 +/- 0.2 eV, consistent with the fundamental energies of creation and migration on Si(001).