Thick GaN layers were deposited by the reaction of gallium with ammonia. The Physical Vapour Transport (PVT) process with NH3 addition is characterized by moderate NH3 flow rates, pressures, and consumption of reactants, by reduced parasitic growth and no NH4Cl formation. Carbon addition to the ammonia results in growth of thicker layers at increased transport rate and in single crystals even at Ga super saturations, which would normally be too high for single crystalline growth. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)