The real-time imaging of reconstruction transitions during molecular beam epitaxy was carried out by means of scanning electron microscopy in the secondary-electron mode. Transition-associated step-bunching, as well as de-bunching, was investigated. In the case of (111)B surfaces that were inclined by 1 towards [¯1¯12], the uniform motion of atomic steps was observed at 620C, with a growth rate of 0.1 monolayer/s under 19 x 19 reconstruction. When the growth temperature was increased to 625C, a 1 x 1 high-temperature reconstruction appeared from the step edges, and step bunching immediately occurred. It was found that the average macro-step spacing increased, with domain size, to a saturation value at a given temperature. With increasing growth temperature, the macro-step spacing increased - to cover hundreds of monatomic steps - until the surface became a pure 1 x 1 reconstruction. However, as soon as the growth temperature was decreased to 620C, step de-bunching occurred within a few minutes; with marked step motion.

H.W.Ren, T.Nishinaga: Physical Review B, 1996, 54[16], R11054-7