The adsorption and migration characteristics of Ga and Al atoms on (100) surfaces were investigated by using reflection high-energy electron diffraction and the alternate deposition of Ga or Al and As4 onto the growing surface. Differing characteristics were found for Ga atoms which were deposited onto a GaAs surface and for Al atoms which were deposited onto an AlAs surface. Excess Ga deposition onto the GaAs surface produced Ga clusters or droplets on the first Ga layer. These dissolved very quickly after As4 deposition and formed flat GaAs layers when the number of Ga atoms was near to 2 or 3 times the surface site number. However, this was not true for Al deposition onto AlAs. Differing characteristics were also found for Ga and Al atoms which were deposited onto the As-stable GaAs surface. All of the results were attributed to the existence of differing migration velocities for Ga and Al atoms.

Y.Horikoshi, H.Yamaguchi, M.Kawashima: Japanese Journal of Applied Physics, 1989, 28[8], 1307-11