Abstract: The growth of GaN films on preliminarily treated Si(001) substrates by chloride–hydride vapor-phase epitaxy through a buffer layer is reported. It is demonstrated that the use of the technology proposed in the study brings about the formation of a Si transition sublayer in the Si substrate, so that further growth on this sublayer provides the formation of columnar GaN grains, between which there is a thin interlayer of the AlN phase. The epitaxial GaN film possesses low residual stresses, which is reflected in high-intensity luminescence.