Boron-Doping Proximity Effects on Dislocation Generation during Non-Planar MPCVD Homoepitaxial Diamond Growth

Epitaxial lateral growth will be required if complex diamond-based device architecture, such as, for example, Metal-oxide-semiconductor Field-effect transistors (MOSFETs) or epitaxial lateral overgrowth (ELO) substrates, need to be developed for high-power applications. To this end, undoped and doped non-planar homoepitaxial diamond were overgrown on (001)-oriented diamond-patterned substrates. Defects induced by both the heavy boron doping and three-dimensional (3D) growth were studied by transmission electron microscopy (TEM). At high methane and boron concentrations, threading dislocations with Burgers vectors b = 1/6 〈211〉, b = 1/2 〈110〉, or both were observed. Their generation mechanisms were established, revealing boron proximity effects as precursors of dislocations generated in boron-doped samples and providing clues as to the different Burgers vectors. The concentration ranges of boron and methane resulting in good crystalline quality depended on the plane of growth. The microwave plasma-enhanced chemical vapour deposition (MPCVD) growth conditions and the maximum boron concentration versus plane orientation yielding a dislocation-free diamond epitaxial layer were determined.