Reconstruction transitions during molecular-beam epitaxy on GaAs(111)B vicinal surfaces studied by scanning electron microscopy

Real-time imaging of reconstruction transitions during molecular-beam epitaxy on a GaAs surface has been performed by scanning electron microscopy in the secondary-electron mode, and reconstruction-transition-associated step bunching as well as debunching behaviors were investigated. On the GaAs(lll)B surface inclined 1 degrees toward the <[(11)over bar2]> direction, uniform motion of atomic steps was observed at 620 degrees C with a growth rate of 0.1 ML/s under root 19x root 19 reconstruction When the growth temperature was raised to 625 degrees C, 1x1 high-temperature reconstruction [(1x1)(HT)] was found to appear from the step edges and step bunching occurred immediately. It was found that the average macrostep spacing increases in accordance with the domain sizes to a saturated value at a certain temperature. With an increase of the growth temperature, macrostep spacing was increased to cover hundreds of monatomic steps until the surface became a pure (1x1)(HT) reconstruction. However, as soon as the growth temperature was lowered down to 620 degrees C, step debunching occurred immediately in a few minutes with remarkable step motion.