The Alx Ga1–xN layers with a wide range of AlN molar fraction (0 < x < 0.6) were grown by ammonia MBE on (0001)‐oriented sapphire substrates using silane as the silicon dopant. The structural, electrical and optical properties of the layers were investigated by atomic force microscopy, X‐ray diffraction, Hall, Raman, photoluminescence and cathodoluminescence measurements. It was found that doping affects surface morphology, dislocation density and luminescence intensity of the Alx Ga1–xN layers. A sharp decrease of the luminescence intensity for the heavily doped GaN and Al0.3Ga0.7N layers was explained by enhancement of the nonradiative recombination rate in degenerate GaN layers and by an increase in the defect concentration in AlGaN layers. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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We report time-resolved and temperature-dependent photoluminescence investigations of green photoluminescence in heavily doped Al x Ga1− x N:Si films grown by molecular beam epitaxy on sapphire substrates. The green band dominates in the photoluminescence spectra of Al x Ga1− x N:Si films with the Al content higher than 0.5. This band is attributed to donor–acceptor and free electron–acceptor transitions involving the same acceptor. Donor and acceptor binding energies of about 50 and 930 meV, respectively, were obtained. The donor was assigned to the Si atom on the Ga/Al site; the acceptor might be the C atom on the N site or a complex comprising a Ga/Al vacancy and a shallow donor.