Sharp-flat reversible change of top of pyramid in gaas molecular beam epitaxy on (111)B patterned substrate

The sharpening and flattening of the top of a pyramid on GaAs(111)B substrate during molecular beam epitaxy (MBE) of GaAs were monitored in real time under a microprobe reflection high-energy electron diffraction/scanning electron microscope (microprobe-RHEED/SEM) installed in a MBE chamber. After the formation of sharp pyramids with {110} side facets, the top of the pyramids was flattened and sharpened reversibly by increasing and decreasing arsenic pressure, respectively. To understand this behavior, we conducted a theoretical analysis based on intersurface diffusion, and we found a good agreement between the calculated and experimental results. Using this knowledge, we succeeded in controlling the size of the top of pyramids in real time.