Solid-state light sources irradiating in the ultraviolet (UV) spectral region are key components in today’s technologies for several applications. Ultrathin GaN layers in AlGaN barriers represent a promising active medium for UV-emitting photonic devices, but a full understanding of their complex excitonic features deserves further investigation. In this work, GaN layers, grown in AlGaN barriers with different heights by metal organic chemical vapor deposition, were studied with the aim to correlate excitonic effects with structural features. It is shown that the UV emission from such structures involves free and bound excitons, as well as free carriers, while the free exciton binding energy is directly and experimentally derived.