Patent ID: 7455729
Filing Date: 2008-11-25
Classification: C30B,H01L

Abstract:
1. Process for making a film of gallium nitride (GaN) starting from a substrate, by depositing GaN by vapour phase epitaxy, characterised in that the GaN deposit comprises at least one vapour phase epitaxial lateral overgrowth (ELO) step, and in that at least one of these ELO steps is preceded by etching of openings: either in a previously deposited dielectric mask, or directly in the substrate, and in that an asymmetry is introduced into the dislocations environment during one of the ELO steps so as to cause the largest possible number of dislocation curvatures, since curved dislocations do not emerge at the surface of the GaN layer thus obtained wherein the asymmetry in induced: (1) by varying growth parameters either by applying an electric field perpendicular to the growth axis, or applying a magnetic field, or by illuminating using a lamp producing UV radiation at about 170 to 400 nm, to cause preferential growth of a single family of facets {11-22},or (2) by making openings with unequal widths or with unequal geometry, either in the dielectric mask or directly in the substrate to apply geometric shapes to the GaN patterns to facilitate the curvature of dislocations.