Small amounts of As residual pressure were found to affect the structure of cubic GaN growing surfaces in molecular beam epitaxy growth, i.e., modification of surface reconstruction structures, stabilization of reconstructed flat surfaces at high substrate temperatures, and preferential growth of the cubic phase. These As surfactant effects are discussed in relation to the atomic arrangement of the As-passivated surface of GaN. It was shown that the quality of cubic GaN epilayers can be improved by utilizing a small amount of As residual pressure. ©1998 American Institute of Physics.