We present an overview on the growth and the optical properties of GaN quantum dots (QDs) embedded in planar AlN grown on the following three different types of substrates: single AlN crystal, AlN on sapphire, and AIN on Si(111). QD density control over three orders of magnitude from 10 8 to 10 11 cm -2 is demonstrated by changing the GaN growth rate. After having established a phase diagram for the QD formation and the critical thickness for the 2D-3D transition, we focus on a comparative study on the optical fingerprint of individual QDs. We identify numerous excitonic complexes in individual GaN QDs and analyze their suitability for single-photon emission at non-cryogenic temperatures as attested by the corresponding g (2) -traces derived from photon correlation measurements. Clear antibunching with g (2) (0)=0.17±0.03 is observed at 300 K, which originates from the decay of single excitons in an individual GaN QD. Finally, an excitation power dependent analysis of the photon statistics reveals the limiting factors for the purity of our single photon sources, provides insight into the physical mechanism of spectral diffusion, and a general pathway towards future optimization, which aims for electrically driven single photon sources operating at 300 K.