The homoepitaxial growth of GaAs(110) thin films by molecular beam epitaxy has been studiedinsituby reflection high‐energy diffraction. RHEED specular beam intensity oscillations were recorded over a wide range of growth conditions in which the substrate temperature, growth rate, V/III flux ratio and the relative amount of As2or As4in the incident arsenic beam were varied. These conditions were plotted to produce a phase map of the growth conditions for which specular intensity oscillations were recordable. RHEED oscillations were obtained over a much wider range of growth conditions when using As2compared to growth using As4. It is shown that this is related to the very different incorporation coefficients of the two arsenic species and reflects the requirement of a high arsenic adatom concentration in order to maintain the 1:1 stoichiometry of the nonpolar (110) surface. ©1995 American Institute of Physics.