A distinct reduction of both the columnar near-interface region and the domain formation were observed in layers grown on AlN and GaN ‘template’ buffers resulting in improved bulk quality and significant smoother film surfaces.

Physica Status Solidi (a)

We report a comparative study of the crystalline quality of thick GaN layers grown by hydride vapour phase epitaxy, using a nitridation and a GaCl pretreatment of the sapphire as well as a reactive sputtered AlN buffer and metalorganic chemical vapour deposition grown GaN ‘template’ layers. The structure quality was investigated using X-ray diffraction measurement and cathodoluminescence spectroscopy and imaging of cross-section of the films. The morphology of the layers was revealed by optical and atomic force microscopy. A distinct reduction of both the columnar near-interface region and the domain formation were observed in layers grown on AlN and GaN ‘template’ buffers resulting in improved bulk quality and significant smoother film surfaces.

A distinct reduction of both the columnar near-interface region and the domain formation were observed in layers grown on AlN and GaN ‘template’ buffers resulting in improved bulk quality and significant smoother film surfaces.

Thick hydride vapour phase epitaxial GaN layers grown on sapphire with different buffers