Epitaxial lateral overgrowth techniques used in group III nitride epitaxy

Selective-area growth (SAG) and epitaxial lateral overgrowth (ELO) techniques used in group III nitride epitaxy are reviewed. Structurally controlled GaN in line patterns and dot patterns was obtained by using the SAG technique. This structural control technique has been applied to field emitters, waveguides, facet lasers and low-dimensional quantum structures. The ELO technique was originally proposed as a way to reduce dislocation density in epitaxial GaN layers and various ELO techniques have been developed recently. For example, facet-controlled ELO (FACELO) is one of the attractive techniques available for reducing dislocation density. The dislocation density is dramatically reduced to of the order of 10^5-6 cm^-2 with good reproducibility. In this article, SAG and ELO techniques related to nitride epitaxy and applications to optical and electronic devices are reviewed. Production of GaN hexagonal pyramids on dot-patterned GaN/sapphire substrates and the FACELO technique are also described as examples of the SAG and ELO techniques.