Effect of SiN treatment on GaN epilayer quality

High-temperature GaN films were grown at 1120 °C and 1080 °C by atmospheric pressure metalorganic vapor phase epitaxy on silicon nitride (SiN)-treated sapphire using a GaN buffer layer grown at 600 °C. The effect of a SiN interlayer has been investigated. We have varied the silane (SiH4) flow from 4 to 20 sccm and the duration of SiN treatment from 60 s to 180 s. These layers have been characterized in-situ by laser reflectometry and ex-situ by atomic force microscopy (AFM) and low-temperature photoluminescence. AFM revealed that GaN grown with optimized SiN treatment shows a terrace-like structure with a reduced density of dislocations of about 5 × 108 cm−2 compared to GaN without SiN treatment. The I2 line is very intense with a 4 meV full width at half maximum. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)