The As pressure dependence of the surface diffusion of Ga adatoms on molecular beam epitaxial (111) B-(001) mesa-etched substrates was investigated by using in situ scanning microprobe reflection high-energy electron diffraction techniques. It was observed, for the first time, that the direction of Ga adatom migration from, or to, the (111)B side-wall changed; depending upon the As pressure. Moreover, the diffusion length of Ga adatoms on the (001) surface, in the [¯110] direction, was found to depend exponentially upon the As pressure. However, it was independent of the direction of lateral migration. The diffusion length of Ga adatoms on the (001) surface, in the [¯110] direction, varied from about 0.25 to 1.2 at 600C, within the present range of As pressures. It was suggested that the lifetime of Ga adatoms, before incorporation into the crystal, depended strongly upon the As pressure.

X.Q.Shen, T.Nishinaga: Japanese Journal of Applied Physics 2, 1993, 32[8B], L1117-9