The growth rates of layers which were grown on a mesa-etched (001) surface were measured by using in-situ scanning microprobe reflection high-energy electron diffraction methods. The diffusion lengths of the surface adatoms of column-III elements were deduced from the gradient of the variation of the growth rate. The diffusion lengths were of the order of one micron for every source/material combination. When metal-organic materials were used as a Ga source, it was found that the diffusion length was larger than that of Ga atoms from a metallic Ga source. Because the substrate temperatures which were used in the present experiments were high enough to decompose trimethylgallium and triethylgallium on the surface, Ga adatoms were considered to be responsible for the surface diffusion. It was concluded that derivatives of the metal-organic molecules, such as methyl radicals, affected the diffusion of Ga adatoms.

T.Isu, M.Hata, Y.Morishita, Y.Nomura, S.Goto, Y.Katayama: Journal of Crystal Growth, 1992, 120[1-4], 45-9