Diffusion-limited kinetics of terrace growth on GaAs(110)

The kinetics of thermal annealing of surface roughness created by low-energy ion bombardment of GaAs(110) is characterized in situ by a low-energy electron diffraction (LEED) spot profile analysis to investigate the underlying diffusion mechanisms involved. The coarsening of the step-and-terrace structure on the partially annealed surface is observed, showing power-law growth of the average terrace width l∼tβ with an exponent β=0.23-0.26 over two orders of magnitude in annealing time t in the temperature range 660-740 K. However, the terrace height distribution is shown to vary little with annealing, providing evidence for an Ehrlich-Schwoebel barrier at step edges. The LEED analysis also detects an additional, low amplitude height distribution contributing an interface width of less than 0.03 nm, which is interpreted as elastic deformation around subsurface defects and exhibits much slower relaxation kinetics during annealing than the terrace growth