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AlxGa1–xN layers up to x = 0.45 are grown on sapphire substrates with different orientations via vapour phase reaction of NH3 with the chlorides of Ga and Al. Epitaxial growth with good crystalline perfection is observed on (0001)‐ and (1102)‐oriented substrates. Indications to the existence of a cubic sphalerite phase in AlxGa1–xN are found. All undoped layers are n‐type conducting with electron concentrations above 1019 cm−3 and show a tendency to lower electron concentrations with rising x. The electron mobility depends strongly on the growth conditions. Optical transmission measurements show the expected increase of the band gap with x. Photoluminescence spectra of undoped layers are dominated by a structure near 3.46 eV independent of x. Some results for Zn‐doped samples are also given.

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