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)