Fabrication and characterization of low defect density GaN using facet-controlled epitaxial lateral overgrowth (FACELO)

Facet structures of GaN grown by epitaxial lateral overgrowth (ELO) via low-pressure metalorganic vapor-phase epitaxy (LP-MOVPE) are controlled by growth conditions such as reactor pressure and growth temperature, where this technique is called facet-controlled ELO (FACELO). The propagation mechanism of the threading dislocations for the different GaN facet structure is investigated. The distribution and density of the threading dislocations are observed by the growth pit density (GPD) method. Two typical models employing the FACELO are proposed; in one model, the dislocation concentrates only on the window area and, in the other model, only in the coalescence region in the center of the mask. In the latter model, the dislocation density is dramatically dropped to the order of 10(6)cm(-2) with good reproducibility. The FACELO GaN shows no tilt of c-axis on the mask area and good optical properties. (C) 2000 Elsevier Science B.V. All rights reserved.