We studied undoped GaAs films grown by metalorganic chemical vapor deposition in a vertical geometry atmospheric pressure reactor. Our results on the surface morphology, carrier concentration and conductivity type and low‐temperature photoluminescence spectra of the films, studied as a function of substrate temperature and As/Ga flux during growth, are generally in agreement with previous studies. In addition, we also report the effect of rotation speed of the substrate during growth. It is found that lower speeds give higher defect density and lessn‐type films and most notably enhance a defect exciton line at 1.5119 eV. From the free‐to‐bound transitions and from the dependence of the intensities of the exciton lines on growth temperature and As/Ga flux we inferred that the acceptors in our films are C, Zn, Mg and donors are those substituting on Ga sites.