Unintentionally doped GaN epitaxial layers with a conventional single low-temperature (LT) GaN buffer layer and with multiple MgxNy/GaN buffer layers were grown on sapphire substrates by metal organic chemical vapour deposition. X-ray photoelectron spectroscopy result reveals Mg 2p core-level spectra from the 12 pairs of MgxNy/GaN buffer layers. The multiple MgxNy/GaN buffer layers exhibited a low nuclei density, increasing the volume of defect-free regions and reducing the dislocations associated with the grain boundaries. Therefore, the GaN with multiple MgxNy/GaN buffer layers reveals an asymmetrical reflection (102) with a small full-width at half-maximum, and a higher mobility, lower background concentration and lower etching pit density than the GaN with the LT GaN buffer layer.

Dislocation Annihilation in GaN with Multiple MgxNy/GaN Buffer Layers by Metal Organic Chemical Vapor Deposition. Y.K.Fu, C.J.Tun, C.H.Kuo: Physica Status Solidi C, 2008, 5[6], 1499-501