In this article, experimental results are presented for the homoepitaxial deposition of a GaN overlayer onto a bulk single‐crystal GaN substrate using molecular beam epitaxy. Transmission electron microscopy shows a superior structural quality of the deposited GaN overlayer when compared to heteroepitaxially grown layers. Photoluminescence shows narrow excitonic emission (3.467 eV) and the very weak yellow luminescence, whereas the bulk substrate luminescence is dominated by this deep level emission. These results show that homoepitaxy of GaN can be used to establish benchmark values for the optoelectronic properties of GaN thin films. ©1996 American Institute of Physics.