Atomic-level in situ real-space observation of Ga adatoms on GaAs(0 0 1)(2 　×4)-As surface during molecualr bemam epitaxy growth

摘要

We study in situ scanning tunneling microscopy (STM) observations of Ga adatoms on the molecular beam epitaxy (MBE) growht front, GaAs(0 0 1)(2×4)-As surface, with a system in which STM and MBE are completely one. It is found that Ga adatoms are self-organized about one unit cell far from the B-step edge and on a missing dimmer row. Moreover, the three Ga adatoms form a trigonal surface structure. And this trigonal changed to a tetragonal strucutre with the addition of one Ga atiom.