Growth of cubic AlN films on sapphire(0001) with atomic scale surface smoothness by pulsed laser deposition

We have previously reported that β-AlN crystallites with diameters of 0.5-1 μm were occasionally grown on sapphire(0001) by pulsed laser deposition, which implied that the migration mobility of the species deposited on the substrate surface might be an insufficient for the film growth of β-AlN. In the present study, in order to enhance the crystal growth of β-AlN, sapphire(0001) substrates with an atomically smoothness (step-sapphire) were employed. The growth conditions of α- and β-AlN extended to higher nitrogen-pressures, as compared to those using normal surface sapphire(0001) substrates (normal-sapphire). This is due to the enhancement in the mobility of the deposited species on the substrate surface.