A transmission electron microscopic study was made of the reduction of defect densities in epitaxial lateral overgrown films. In the case of standard one-step epitaxial lateral overgrowth, the propagation of defects under a mask was blocked, whereas defects in the window region threaded up to the surface. An alternative 2-step method was proposed. In the first step, dislocations close to the edge of the (00•1) top facet bent at 90º; thus producing a marked reduction in the density of defects above the window. After coalescence, induced by lateral growth during the second step, dislocations were observed mainly in the coalescence boundaries.

Reduction Mechanisms for Defect Densities in GaN using One- or Two-Step Epitaxial Lateral Overgrowth Methods P.Vennéguès, B.Beaumont, V.Bousquet, M.Vaille, P.Gibart: Journal of Applied Physics, 2000, 87[9], 4175-81