Epitaxial Growth Of Gallium Nitride

Abstract

The heteroepitaxial growth of GaN thin films by metalorganic chemical vapor deposition on (0001) surfaces of sapphire and SiC substrates containing an intermediate buffer layer is reviewed. The process steps in the two‐step growth of GaN on the surface of sapphire, namely, H2 etching, nitridation and the deposition and annealing of the low temperature nucleation layer are described within the context of their effect on the polarity of the final GaN surface. The origins of dislocations in GaN films grown on sapphire are also considered. The surface preparation techniques and buffer layers that influence the defect populations in the GaN films grown on SiC are also detailed. The effect of the substrate surface and the buffer layer/GaN microstructural evolution is emphasized. A brief overview summarizing the lateral overgrowth techniques used to achieve reduced dislocation densities in GaN is also presented.