Abstract
Using a scanning tunneling microscope, we examine the evolution of the surface configuration of GaAs(001) upon annealing after molecular-beam-epitaxy growth interruption. Soon after growth interruption, the surface exhibits many two-dimensional islands elongated along the [11¯0] direction and a ragged step configuration. Continuous annealing after growth interruption causes changes in the surface topography. Annealing for 2 min makes the surface very smooth by decreasing the number of islands and smoothing the step shapes. Further annealing for about 20 min causes step bunching. The decrease in the number of islands and smoothing of step shapes are explained by shortening of the total step length.