Pendeo-epitaxy versus lateral epitaxial overgrowth of GaN: A comparative study via finite element analysis

Recent studies of the structural quality of GaN stripes grown selectively v ia lateral epitaxial overgrowth (LEO) and pendeo-epitaxy (PE) or maskless l ateral epitaxy, reveal that the regions of lateral growth exhibit four-to-f ive orders of magnitude lower density of dislocations compared to the regio ns of vertical growth, In both cases the crystallographic templates for the lateral growth are the {11 (2) over bar 0}, {1 (1) over bar 00}, or the {1 (1) over bar 01} side facets of the GaN. The examination of the morphology of the top surfaces. side facets, and interfaces of the LEO- and PE-GaN st ripes with the underlying and adjacent interfaces, reveal their striking si milarity with the thermally generated stress/strain gradient profiles as ca lculated via finite element analysis. A comparison between the stress distr ibution as a result of the mismatches in the coefficients of thermal expans ion among the films in the structures, grouped in four types with:different geometries will be presented: (1) conventional LEO-GaN, (II) conventional LEO-GaN case without SiO2 layer, (III) PE-GaN mode A, and (IV) PE-GaN mode B.